Shares in England cricket team sponsor Brit Insurance have leapt 20% after the firm rejected a takeover approach.
In a statement after the market closed on Thursday the insurer confirmed that it had received a proposal but said it "significantly undervalues" the group.
A further statement on Friday revealed the approach was made by US private equity firm Apollo.
The unsolicited proposal was worth £10 a share, marking a significant premium on Thursday's closing price of 729p.
When trading began on Friday, shares rocketed above 900p. By early afternoon they were trading at 878p.
Brit became the England cricket team sponsor in January, and also sponsors Surrey County Cricket Club and its ground, the Oval.