Competitive
tendering assumes independent bids and genuine alternatives. Bid rigging
quietly destroys that assumption while keeping its outward shape intact. UK
public-sector procurement expenditure reached approximately £461 billion in
2025/26 – equivalent to around a third of public spending – so even a small
erosion of genuine competition carries a substantial cost to taxpayers, and to
private buyers who rely on the same tendering discipline.
The damage
extends well beyond price. Collusive bidding can suppress quality, blunt
innovation, restrict market access and quietly corrode confidence in
procurement decisions across both sectors. Buyers may believe rivalry has
tested value for money when none existed. Where the same suppliers meet
repeatedly, coordination can embed itself for years within relationships that
look, on paper, like routine competitive purchasing.
Bid rigging takes
several recognised forms: cover pricing, bid suppression, bid rotation,
deliberately uncompetitive tenders and market sharing. These techniques can
operate alone or in combination, often reinforced by compensation payments,
future work or subcontracting. Their power rests on deception – buyers must
believe rivals are competing independently while, privately, those rivals have
replaced uncertainty with an agreed, protected outcome.
Some markets make
coordination easier to organise and sustain. Concentrated supply, predictable
demand, high entry barriers, repetitive tender lists and entrenched incumbency
all help competitors recognise one another and settle into stable patterns. Publishing
more commercially sensitive information than necessary can strip away the
uncertainty that keeps rivals honest, particularly when approved lists remain
closed, or suppliers feel obliged to bid regardless of their appetite.
Protecting
competition demands more than collecting several quotations or following a
compliant process. Procurement teams need to understand market structure,
encourage credible participation, manage information carefully and recognise
behavioural patterns across competitions. Withdrawals, predictable winners,
repeated losers, unexplained subcontracting and stable allocations may each
have an innocent explanation, but together they can expose coordinated conduct
that a single tender file would never reveal.
What Is Bid Rigging?
Bid rigging
occurs when businesses expected to compete instead coordinate secretly to
decide who wins, at what price, or to what standard. The tender can still look
competitive – several apparently separate bids arrive – while rivalry has
quietly been switched off. Agreements might predetermine a winner, inflate
other bids, engineer withdrawals, or divide the market, allowing competitors to
protect margins while narrowing the buyer’s negotiating room.
The deception is
hard to spot precisely because every procedural step still happens. Invitations
go out, tenders arrive, evaluation is completed, a winner emerges. Behind that
routine, however, competitors may already have agreed who should win and how everyone
else should behave. Cover pricing, suppression and rotation each manufacture a
plausible-looking field of independent bids while quietly substituting a
collectively engineered result.
The scale to
which such conduct can extend was demonstrated in 2009, when the Office of Fair
Trading found that 103 construction firms had engaged in bid rigging across 199
tenders between 2000 and 2006. Combined fines exceeded £129 million – then the
largest cartel penalty imposed by a UK competition authority – covering
projects worth more than £200 million, including schools, hospitals,
universities and private housing developments.
A separate CMA
investigation later showed comparable conduct involving both public and private
buyers. In March 2023, ten construction firms were fined nearly £60 million for
rigging bids across 19 demolition and asbestos-removal contracts worth over
£150 million, awarded between 2013 and 2018 for sites including a Metropolitan
Police training centre, Oxford University, Bow Street Magistrates’ Court and
Selfridges.
Both cases now
sit within a considerably tougher legal framework. Since the Procurement Act
2023 came fully into force in February 2025, a supplier found by the CMA or
another relevant regulator to have engaged in cartel conduct, such as bid
rigging, may fall within a mandatory exclusion ground. The central debarment
regime can also result in exclusion from covered public procurements for up to
five years.
The scale of what
is at stake is not confined to the UK. The OECD estimates that public
procurement accounts for around 13% of GDP across its member countries, and its
research suggests that successful bid-rigging cartels can inflate prices by
around 20% compared with genuinely competitive tendering – a level of harm that
helps explain why detection now matters as much to commercial reputation as to
legal compliance.
Cover Pricing
Cover pricing
happens when a bidder deliberately submits a tender designed to lose, usually
because competitors have already agreed who should win. The losing bid may be
inflated or otherwise weakened just enough to look credible without threatening
the chosen supplier. Buyers therefore receive what appears to be several
independent offers while competitive pressure has quietly disappeared, allowing
the intended winner to charge more than a genuinely contested tender would
allow.
The construction
sector exposed the practice at scale: cover pricing accounted for most of the
OFT’s 2009 findings, and in eleven separate tendering rounds every losing bid
submitted was a cover bid, meaning the nominal winner faced no genuine rival at
all. A firm that submitted a deliberately uncompetitive price could remain on a
client’s approved list for future work, quietly entrenching the same behaviour.
A later CMA case
showed how precisely rivals can choreograph a losing bid. One demolition firm
supplied a competitor with its own pricing document and instructed it to “go
some 8% to 10% above this”; a different rival was told to price “10% to 12%
above.” In a separate exchange, a firm was warned that its bid was “far too
close” and needed to increase substantially, while the other’s bid decreased.
Cover pricing
damages a tender even where the intended winner might genuinely have been the
strongest bidder, because it removes every incentive for rivals to sharpen their
pricing, improve quality, or offer better delivery terms. It can also mislead
buyers into believing a tender list is more competitive than it actually is,
discouraging them from inviting additional, genuinely independent suppliers who
might otherwise have bid for the work.
Bid Suppression
Bid suppression
occurs when competitors agree that one or more of them will not tender, decline
an invitation, or withdraw a bid already submitted, narrowing the field that a
favoured supplier faces. Unlike cover pricing, no artificial losing bid is
necessarily needed – the manipulation removes rivals from contention, improving
the designated winner’s prospects while weakening the buyer’s ability to secure
genuine value.
The OECD’s 2025
Guidelines for Fighting Bid Rigging in Public Procurement identify suppression
as one of the principal collusive techniques, alongside cover pricing, rotation
and market allocation. A buyer might invite several capable firms yet receive
only one or two genuine tenders because competitors have privately agreed to
stand aside – a pattern that can affect public authorities and commercial
buyers alike, particularly within small, familiar supplier pools.
The US Department
of Justice has prosecuted dozens of real estate investors for using this exact
mechanism at public foreclosure auctions across Alameda, Contra Costa, San
Francisco, San Mateo, and San Joaquin counties in California. Conspirators
agreed not to bid against one another, then held secret secondary “rounds”
auctions to divide the resulting profit; more than 65 individuals had pleaded
guilty or been convicted in the investigation by 2017.
Genuine reasons
for non-participation exist – insufficient capacity, unsuitable specifications
or shifting commercial priorities can all explain a declined invitation.
Concern grows where the same businesses repeatedly abstain, withdraw
unexpectedly, alternate participation, or later receive subcontracts from the
eventual winner. UK procurement guidance treats non-participation by likely
bidders as a possible red flag warranting closer pattern analysis rather than
automatic suspicion.
Bid Rotation
Bid rotation
occurs when competitors agree to take turns winning contracts rather than
competing independently each time. Participants may all submit tenders, but the
designated winner offers the strongest price, while the others deliberately
lose, thereby distributing contracts, values, or market share among themselves
by agreement. Individual procurements can look entirely competitive even though
the sequence of outcomes has been settled well in advance.
The OECD notes
that conspirators may rotate an equal number of contracts, an equal value, or a
share reflecting each firm’s market position, often disguising the pattern by
combining rotation with cover pricing or suppression. A single tender may
reveal nothing unusual to a buyer examining it alone; only by reviewing awards
across several years does a suspiciously predictable sequence of winners emerge.
A 2020 US case
illustrates the mechanism precisely. The Department of Justice charged Carter
Brett, an account executive at a large flooring manufacturer, with
orchestrating a bid-rotation conspiracy among three commercial flooring
installation firms so that a designated company would win contracts at a
Chicago-area community college between 2013 and 2017, alongside a parallel
kickback scheme run through a shell company he controlled.
Rotation can
affect public and private buyers wherever contracts recur. The Department of
Justice notes that conspirators may divide work by an equal number or value of
contracts, by market share, or by operational convenience, thereby stabilising
cartel members’ revenues while denying the buyer the price pressure,
innovation, and service improvements that genuine rivalry should generate over
a series of tenders.
Detection,
therefore, depends on reading procurement history as a pattern rather than
judging each tender in isolation. Predictable alternation between winners,
stable market shares, recurring losers and suppliers winning roughly equal
shares of work can each have an innocent explanation individually, but rotation
combined with cover bids, withdrawals, subcontracting or direct contact between
competitors gives investigators considerably stronger grounds to act.
Complementary and Deliberately Uncompetitive
Bids
Complementary
bids are tenders deliberately designed to lose while giving a procurement the
appearance of genuine rivalry. A supplier might submit an excessive price,
unacceptable contractual terms, incomplete compliance information, or a
weakened technical response because another competitor has already been chosen
as the winner. The defining feature is coordination: the bidder is not
genuinely competing but is only supporting an agreed outcome.
US antitrust
guidance describes complementary bidding as competitors submitting deliberately
unattractive offers, sometimes engineered to fail tender requirements outright,
so that a chosen conspirator wins. Their presence can reassure a buyer that
adequate competition exists – particularly where procurement rules require
several quotations – while concealing the fact that only one participant ever
submitted a genuinely competitive proposal.
The UK demolition
cartel discussed above is a clear domestic example. The CMA found that firms
submitted bids deliberately priced to lose and, on occasion, offered a
deliberately poorer service, creating the appearance of independent
alternatives to predetermined winners across both public and private sites
affected by the scheme.
A deliberately
uncompetitive bid should never automatically be read as evidence of collusion.
High prices can reflect genuine capacity constraints, mobilisation costs or
reluctance to accept onerous terms, while a weak quality response may reflect
poor tendering. Suspicion strengthens where losing bids show recurring price
gaps, implausible qualifications, identical drafting errors or unusual
pre-tender contact between competitors.
Compensation for Losing Bidders
Compensation
arrangements arise when a bidder that has agreed not to compete genuinely
receives something of value from the predetermined winner – a direct payment, a
subcontract, future work, a consultancy fee, or another benefit. These
arrangements sustain a cartel because losing participants still profit from
cooperating, which reduces any incentive to break ranks and submit an
independently competitive tender.
Compensation is
conceptually distinct from the other techniques already described. Rotation
decides whose turn it is to win; cover pricing manufactures a losing tender;
suppression removes a rival altogether. Compensation instead rewards
cooperation after, or alongside, those arrangements, and government guidance is
explicit that several mechanisms frequently operate together within a single
procurement exercise.
The OFT’s 2009
construction investigation, discussed above for its scale, also found six
compensation payments ranging from £2,500 to £60,000, facilitated by false
invoices. Modest compared with the sums seen more recently, these payments
nonetheless showed that even a cover-pricing-led scheme can be reinforced by a
secondary layer of financial reward for cooperating losers.
The later
demolition cartel showed compensation operating at a far larger scale. Five of
the ten firms were, on at least one occasion, involved in arrangements
compensating designated losers, with one payment exceeding £500,000; false
invoices again disguised the true purpose. The disparity between the two cases,
sixteen years apart, illustrates how compensation sums have grown alongside
contract values.
Subcontracting
can achieve the same economic effect without a cash payment changing hands: a
supplier may agree to stand aside, submit a cover bid or weaken its tender in
exchange for work from the eventual winner. It is not inherently suspicious,
since genuine capability or capacity reasons often justify it, but recurring,
unexplained transfers of work to previous losers merit closer scrutiny.
Subcontracting Between Supposed Competitors
Subcontracting
between competitors is common and often entirely legitimate, particularly where
specialist capability, regional coverage or extra capacity is genuinely
required. Concern arises when a bidder that competed unsuccessfully
subsequently receives substantial work from the successful supplier with no
clear operational justification. OECD guidance identifies this pattern as a
possible warning sign, because subcontracting can sometimes reward a competitor
that had agreed not to compete independently.
UK guidance
similarly flags cases where a winning bidder later subcontracts work to a
supplier that submitted a higher tender as a possible indicator of bid rigging.
Concern strengthens where the same firms repeatedly swap prime and subcontract
roles, unsuccessful bidders receive disproportionate work, or participation
across a series of tenders appears choreographed rather than independently
decided by each party.
Subcontracting
alone never establishes unlawful coordination. A winning contractor may
genuinely need specialist expertise, local labour, equipment or extra resources
that a competitor can supply efficiently. Procurement teams should examine
context, rationale and patterns over time rather than infer collusion from a
single appointment, focusing scrutiny on subcontracts that follow predictable
outcomes or lack transparent justification.
Supply chain
visibility is now easier to test than it once was. Under the Procurement Act
2023, larger public contracts carry greater transparency requirements regarding
subcontracting arrangements, while unexplained work flowing to previously
unsuccessful bidders is the type of anomaly that increasingly sophisticated
data analytics can help procurement teams and competition authorities identify
in tender data.
Dividing Contracts by Geography, Customer or
Work Type
Market allocation
occurs when competitors divide opportunities between themselves by geography,
customer, contract or work type, agreeing not to compete genuinely outside
their allotted territory or account. The arrangement may involve abstaining
from certain tenders, submitting cover bids, or deliberately weakening an offer
so the designated supplier wins, preserving established market shares and
customer relationships at the buyer’s expense.
Geographical
allocation can produce suspiciously stable regional winners; customer
allocation lets suppliers retain particular clients without serious challenge;
work-type allocation can see businesses informally reserving specialist
services or contract categories for different cartel members. Individual
outcomes may each look commercially plausible, but a pattern across
procurements can reveal that competitors rarely challenge one another’s
established territory.
The UK water-tank
cartel clearly illustrates customer allocation. The CMA found that three
suppliers of galvanised steel water tanks – used for water storage in schools,
hospitals and other buildings – had shared the market, fixed prices and rigged
bids between 2005 and 2012, and fined them a combined £2.6 million; a fourth
participant escaped any fine after reporting the cartel under the CMA’s
leniency programme.
Private-sector
tendering is equally exposed. In 2018, the CMA fined two of the main suppliers
of bagged household fuels, CPL and Fuel Express, more than £3.4 million for
rigging tenders to supply Tesco and Sainsbury’s: for each contract, one
supplier deliberately submitted a higher, losing bid so the existing supplier
could retain its customer, protecting an established relationship from genuine
competition.
Multiple Forms of Collusion in the Same Tender
Collusive
tendering rarely depends on a single technique. Competitors can combine
suppression, cover pricing, rotation, market allocation, and compensation
within a single procurement or across a continuing series of contracts. One
supplier may be selected to win, another may submit an inflated bid, a third
may withdraw, and unsuccessful participants may later receive payment or
subcontract work, together manufacturing convincing evidence of competition
while secretly controlling the outcome.
The OECD’s 2025
Guidelines are explicit that these techniques are not mutually exclusive: cover
bidding can support a rotation arrangement, market allocation can determine
which supplier receives which customers or regions, and suppression can remove
unwanted rivalry so that cover bidders alone preserve the appearance of
competition. Compensation then distributes the resulting cartel profits and
discourages anyone from breaking ranks.
A simple version
might begin with competitors allocating a contract to Supplier A, while
Supplier B submits a cover price well above A’s, Supplier C declines to bid,
and Supplier D withdraws before evaluation. On the next contract the roles
rotate. Over time, work can be divided by value, geography or customer, giving
each participant an agreed share without ever appearing to coordinate.
The UK water-tank
cartel already discussed is a good illustration of overlap in practice: the
same three suppliers were found guilty simultaneously of price-fixing, market
sharing and bid-rigging, quoting a lower price only for customers already
allocated to them while rivals quoted higher “shadow” prices to preserve the
appearance of a contest that had, in reality, already been decided in advance.
The demolition
and construction cases introduced earlier in this article showed the same
overlap: cover bidding sat alongside compensation payments in the demolition
cartel, just as cover pricing sat alongside compensation payments in the 2009
construction case, sixteen years apart. That consistency – a headline technique
reinforced by a secondary payment mechanism – is itself a recognised warning
sign for investigators.
For procurement
teams, the lesson is to weigh suspicious indicators collectively rather than in
isolation. A declined invitation may be legitimate, an expensive bid may
reflect real costs, and subcontracting may have sound reasons. Concern grows
when these features recur alongside predictable winners, territorial patterns,
unusual withdrawals or payments between competitors – connected signals that no
single tender document would expose alone.
Conditions That Make Collusion Easier
Collusion becomes
easier where only a handful of credible suppliers can meet a buyer’s
requirements. High market concentration reduces the number of relationships a
cartel must manage and makes any deviation easier to spot. The OECD identifies
concentrated markets, similar supplier structures and limited entry as key
facilitating conditions: where rivals know one another well and face few
outside challengers, coordinating prices or winners becomes considerably easier
to arrange and sustain.
Repeated
procurement creates additional opportunities, since the same suppliers meet frequently
and can share contracts over time. Predictable demand lets participants
anticipate future opportunities, rotate winners, and discipline a business that
breaks ranks by competing aggressively. The risk is acute for recurring public
contracts, maintenance programmes and framework call-offs, but private buyers
purchasing the same goods repeatedly face comparable exposure.
Standardised
requirements can compound the risk because competitors have fewer variables
left to disagree on, while high entry barriers – capital requirements,
specialist accreditation, scarce equipment or lengthy qualification processes –
shield incumbents from disruptive newcomers. Poorly designed qualification
criteria that unnecessarily exclude SMEs or alternative delivery models can
unintentionally reinforce exactly the conditions that make coordination easier
to sustain.
The CMA’s ongoing
investigation, opened in December 2024 and expanded in January 2026, into
suspected bid rigging involving roofing and construction services shows that
these risks can persist even within closely regulated markets. Its scope now
extends beyond Department for Education school-improvement contracts to work
supplied to other public and private-sector bodies. No findings of wrongdoing
have been made yet, but the investigation reinforces the need for scrutiny in
concentrated, repeat-tender markets.
When Transparency Can Assist Collusion
Transparency is
essential to accountable procurement, allowing suppliers, auditors, taxpayers
and other stakeholders to see how opportunities are advertised, evaluated and
awarded. But transparency is not the same as unrestricted disclosure. The OECD
warns that information exceeding legal or operational needs can facilitate
collusion: where rivals learn who is bidding, what others are charging, or how
future demand will arise, uncertainty between them falls sharply.
The danger is
greatest in repeated markets, where information from one competition helps
cartel members police the next. Publishing bidder identities, detailed losing
prices, scoring data or precise future procurement values can reveal whether
participants followed an agreed rotation or pricing structure. The OECD’s 2025
Guidelines recommend avoiding the routine disclosure of bidder identities,
reconsidering public bid openings, and controlling the release of sensitive
information after award.
UK public
procurement requires openness, but the framework recognises legitimate
commercial sensitivity. Guidance under the Procurement Act 2023 identifies
detailed pricing, profit margins, overheads, financial models, and information
affecting future re-bids as potentially sensitive; contracting authorities must
balance disclosure against the public interest rather than automatically
withhold it, aiming to ensure scrutiny of spend without exposing a supplier’s
competitive strategy.
Private buyers
face the same risk despite different publication duties. Revealing incumbents’
rates, competitors’ identities or confidential bid information during debriefs
or supplier meetings can inadvertently facilitate coordination, and CMA
guidance confirms that competitively sensitive information can restrict
competition even when exchanged indirectly through an intermediary, including a
public authority acting as an unwitting conduit between rival bidders.
A 2016 CMA
investigation into UK modelling agencies shows how damaging visibility of
rivals’ pricing intentions can be even outside formal procurement. Five
agencies and their trade association were fined £1,533,500 for regularly
exchanging pricing information and sometimes agreeing minimum fees when
negotiating with fashion retailers between April 2013 and March 2015, replacing
independent commercial judgement with coordinated behaviour.
Effective
transparency, therefore, requires judgement: enough information to support
scrutiny, fairness, and market access, but not so much that it gives
competitors a monitoring system. Supplier questions can be answered
anonymously, bidder identities can be withheld during the competition, and
procurement plans need not reveal every value and timing in advance. The
principle is simple – transparency should expose the buyer’s decisions, not the
market’s behaviour.
Incumbency and Closed Supplier Markets
Incumbency
becomes a competitive risk when buyers repeatedly invite the same suppliers and
rarely test whether credible alternatives exist. Familiarity can reduce
transaction costs and reassure about delivery, but a stable bidder group also
allows competitors to observe one another closely over time. The OECD warns
that repetitive bidding and limited entry can help suppliers allocate
contracts, monitor compliance and discipline rivals who break ranks.
Closed supplier
markets can emerge through narrow frameworks, restrictive approved lists or
disproportionate qualification requirements that keep new businesses out.
Excessive turnover thresholds, unnecessary experience requirements or lengthy
accreditation processes can unintentionally protect incumbents. OECD guidance
recommends opening tenders to as many credible suppliers as possible and
ensuring pre-approved lists can readily accept new entrants, including
mid-procurement wherever practicable.
Repeated tender
lists strengthen coordination because competitors learn one another’s pricing
patterns, capacity and appetite for work. Where the same firms compete for
predictable contracts, rotating winners or preserving customer relationships
becomes easier, while new entrants disrupt that stability by introducing
genuine uncertainty. The OECD treats a significant price drop following a bid
from a new or infrequent supplier as a possible sign that prior competition had
been constrained.
The UK office
fit-out cartel demonstrates the danger of a narrow, familiar market. Between
2006 and 2017, six firms used cover bidding across 14 refurbishment contracts
in London and the Home Counties, with clients including a low-cost airline, a
City law firm and a further-education college in East London; five of the six
were fined a combined £7 million, while the sixth escaped any penalty by
reporting the conduct first.
Incumbency is not
itself evidence of collusion, and repeat appointments may reflect strong
performance or genuine value. Risk rises when incumbents face little new
competition, tender lists change little, regular bidders divide wins
predictably, or unsuccessful firms continue to participate despite having no
realistic prospects. Refreshing supplier pools, applying proportionate entry
criteria and researching wider markets all help reduce that exposure over time.
Procurement Practices That Accidentally
Encourage Cover Bidding
Procurement
practices can unintentionally encourage cover bidding when suppliers feel
obliged to participate despite having little interest in winning. A business
may fear removal from an approved list or damage to a customer relationship if
it repeatedly declines invitations, so instead of a competitive tender it
offers an intentionally high or weak one, creating the appearance of
competition without any real competitive pressure behind it.
The CMA
specifically advises procurers to avoid tender-list management that pushes
firms to bid when they do not want the work. Requiring three quotations
achieves little if two suppliers participate merely to protect their status. A
CMA survey of the construction sector found only 6% of firms were familiar with
competition law, and a quarter saw nothing wrong with discussing bids and
agreeing who should win.
Rigid approved
lists compound the problem by narrowing the field before a requirement is even
advertised. The OECD recommends allowing suppliers to join pre-approved lists
during procurement where practicable, and avoiding invitations that repeatedly
target the same small group. Wider participation introduces uncertainty; closed
lists, by contrast, create stable groups whose members grow accustomed to
exchanging non-competitive bids over time.
Frameworks and
repetitive quotation exercises create similar risks when buyers seek bids from
every appointed supplier regardless of capacity or appetite. A contractor with
no intention of performing the work may still submit a protective price rather
than decline the work. Once this becomes routine, genuine and artificial
tenders become harder to distinguish, so call-offs should be designed around
credible interest and meaningful competition.
The office
fit-out cartel again illustrates the risk in practice: cover bidding across 14
London-area contracts between 2006 and 2017 shows how apparently routine
competitive tendering can conceal deliberately non-competitive offers, whatever
sector or client is involved.
Good procurement
design reduces these incentives without discouraging honest non-participation.
Buyers can refresh tender lists, broaden market engagement, apply proportionate
qualification criteria and make clear that declining an unsuitable opportunity
will not prejudice future invitations. Monitoring suppliers who repeatedly bid
but never win – an OECD-identified warning sign – helps ensure every invitation
seeks a genuinely independent, competitive bid.
Summary – Recognising the Illusion of
Competition
Bid rigging turns
competitive tendering into a controlled process in which suppliers appear to
compete while secretly deciding who wins, at what price and under what
conditions. Cover pricing, suppression, rotation, and deliberately
uncompetitive bids can each distort a procurement on its own, but their impact
multiplies when combined, leaving tenders that satisfy every procedural
requirement while quietly removing the rivalry needed to protect value and
quality.
Compensation
arrangements strengthen these schemes by rewarding suppliers that agree to
lose, withdraw or stay away altogether. Payments, future work or subcontracts
can make continued cooperation commercially attractive and help preserve a
cartel over years. Subcontracting between apparent competitors is not
inherently suspicious, but repeated, unexplained transfers of substantial work
to unsuccessful bidders become significant alongside other evidence of
coordination.
Market sharing allows
competitors to preserve territories, customers, or specialist work by avoiding
direct competition in areas allocated to others, often through the same
suppression, cover-bidding, or rotation techniques already described.
Individual tenders can look entirely plausible in isolation. At the same time,
several years of awards reveal stable shares, repeated winners and limited
genuine challenge between established rivals – a pattern only visible in
aggregate.
Certain market
structures make coordination easier to sustain: concentrated supply,
predictable demand, repeated procurements, standardised requirements, and high
entry barriers enable competitors to encounter one another regularly and
anticipate future opportunities, while closed tender lists and strong
incumbency reinforce those conditions. None of these factors proves collusion on
its own, but together they create an environment in which coordinated behaviour
becomes far easier to hide.
Transparency
remains fundamental to accountable procurement, yet excessive disclosure can
unintentionally assist coordination. Publishing detailed losing prices, bidder
identities or commercially sensitive information can help competitors monitor
whether agreed behaviour is being followed, so effective transparency requires
judgement: enough disclosure to support scrutiny and fairness, while protecting
the specific information that would otherwise reduce genuine uncertainty
between rival suppliers.
Detection now
benefits from tools earlier investigations never had. Since February 2025, the
Procurement Act 2023 has strengthened the consequences of proven cartel conduct
through mandatory exclusion and the debarment regime, while the CMA is
increasingly using data analytics and artificial intelligence to identify
suspicious bidding patterns. The strongest defence remains unchanged, though:
broad market access, disciplined information management, and procurement teams
able to recognise when a competitive process conceals a coordinated result.
Additional
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Further Reading
- OECD (2025), OECD Guidelines for Fighting Bid Rigging in Public Procurement (2025 Update), OECD Publishing, Paris – oecd.org
- Office of Fair Trading, Construction industry in England: bid-rigging, Case CE/4327-04 – gov.uk/cma-cases/construction-industry-in-england-bid-rigging
- Competition and Markets Authority, “Construction firms fined nearly £60 million for breaking competition law by bid rigging”, press release, 23 March 2023 – gov.uk
- Competition and Markets Authority, “Case study: lessons learnt after demolition companies fined over £60 million for bid-rigging” – gov.uk/government/case-studies
- Competition and Markets Authority, “Office design and fit-out cartel case study” – gov.uk/government/case-studies/office-design-and-fit-out-cartel-case-study
- Competition and Markets Authority, “Water tanks cartel case study” – gov.uk/government/case-studies/water-tanks-cartel-case-study
- Competition and Markets Authority, “Household fuel cartel case study” – gov.uk/government/case-studies/household-fuel-cartel-case-study
- House of Commons Library, “Procurement statistics: a short guide”, CBP-9317 – commonslibrary. parliament.uk
- Procurement Act 2023 (legislation.gov.uk) and Cabinet Office guidance on supplier exclusion and debarment; see also British Business Bank, “Navigating competition exclusions in the Procurement Act 2023”
- US Department of Justice, Antitrust Division, Price Fixing, Bid Rigging, and Market Allocation Schemes: What They Are and What to Look For – justice.gov/atr
