 Coupa Software Inc shares raced up nearly 24 in New York as it announced that private equity group Thomas Bravo was buying it for 6.15 billion in cash. The software firm will receive 81 per share under the deal - 30.5 higher than the shares closing level on December 9 and a 77.2 premium to the stock price on November 22 when takeover interest in the company was first reported. 