MIKE Ashley’s Sports Direct International has made a £43m bet that shares in troubled supermarket Tesco will rally after their recent slump.

The billionaire, who owns Newcastle United, has agreed with Goldman Sachs to sell the bank 23 million shares at a set price in the future. Under the terms of this 'put-option', if Tesco shares fall below this exercise price, then Sports Direct either has to buy shares in the market to fulfil the bargain with Goldman, or pay the bank the difference. In either case Mr Ashley’s business will lose out.

However, if Tesco shares recover, Mr Ashley will receive a premium reflecting the increase. Sports Direct would not reveal the exercise price or when the option would expire.

Sports Direct said it was required to put up cash as collateral for the 23 million shares, which represent 0.28 per cent of Tesco. It said: “After taking into account the premium it will receive, Sports Direct’s maximum exposure under the put option is limited to approximately £43m.”

Tesco shares have lost around 15 per cent of their value this week after it unveiled a surprise profit warning on Monday and admitted to accounting errors which led it to overstate its first-half profit by £250m.

"This investment reflects Sports Direct's growing relationship with Tesco and belief in Tesco's long-term future," the company said.

Its punt on a recovery in the supermarket chain's value followed a decision by Tesco's third-largest shareholder to cut its stake.

The world's biggest investment firm BlackRock sold more than £150m-worth of shares, taking its stake below five per cent.

The sell-off came to light after credit ratings agency Standard & Poor's joined Moody's and Fitch in warning of a potential downgrade to Tesco's credit rating.

It said its action would depend on the findings of the chain's investigation.

It has also emerged that Tesco executives may have to appear before MPs to explain its profit guidance mistake.