Carillion, a UK construction giant, collapsed overnight with £7 billion in debt

Carillion was one of Britain's largest construction and facilities-management companies, employing tens of thousands and holding major government contracts, from hospitals to railways. On the surface it looked like a stable blue-chip firm. Beneath, it was in trouble: it had grown by winning contracts at aggressively low bids, some of which lost money, and it had used aggressive accounting to keep its profits and dividend looking healthy.

In 2017 the cracks became public. Carillion issued a series of profit warnings, writing down billions of pounds on contracts that had gone bad, and it emerged that the company had been recognizing revenue and profits ahead of the cash it was actually earning. Its debt had ballooned to about £7 billion, and its pension deficit was enormous.

In January 2018, after rescue talks with banks and the government failed, Carillion went into compulsory liquidation — one of the largest corporate collapses in UK history. The failure cost tens of thousands of jobs, left a huge pension deficit, and disrupted public services across the country. A parliamentary inquiry condemned the company's directors and its auditor KPMG. Carillion became a byword for aggressive accounting, reckless bidding, and corporate governance failure.