1 April 2004
Nottingham University Hospitals NHS Trust discovers irregularities on tenders. It alerts the OFT and an inquiry into the industry begins.
27 July 2005
The OFT reveals it has searched the premises of 22 Midlands firms to find evidence of collusive tendering.
22 March 2007
The OFT claims it has uncovered £3bn of rigged construction bids. It appeals to companies not yet inspected to come clean.
25 May 2007
Kier becomes the first quoted company to admit it is under investigation and reveals 20 of its tenders are being examined.
30 May 2007
Rok announces it is being probed, and hours later Galliford Try follows suit. Other firms, including Balfour Beatty and Interserve, reveal the same.
The Construction Confederation says it is to lead a joint representation to the OFT to appeal for leniency.
Concern emerges that public sector clients could blacklist firms probed in inquiry. Highways Agency believed to be checking if its firms are included.
17 April 2008
The OFT releases a statement of objections against 112 firms, accusing them of bid-rigging and anti-competitive behaviour.
24 April 2008
It emerges that Balfour Beatty subsidiary Mansell is implicated in the more serious allegations of making compensation payments.
19 December 2008
Contractors under investigation are told they will have to wait up to six months longer than expected to hear if they will be fined.
11 September 2009
Building reveals that the OFT has dropped charges against up to a dozen builders, citing lack of evidence.
22 September 2009
The OFT slaps fines on 103 firms, totalling £130m. Companies face average penalties of £1.26m, or 1.14% of their annual global turnover.