The rejection threatens Silicon Valley’s favoured approach to building firms. The formula relies on gobs of money from venture capitalists to paper over losses with the expectation that Wall Street investors will eventually buy shares and make everybody rich. If mutual funds and pension funds are no longer willing to buy once the firms go public, fledgling entities are unlikely to find funding in the first place. “When the IPO market is hurting, it has a domino effect on valuations and venture capital deals,” said Steven Kaplan, professor (finance & entrepreneurship), University of Chicago. If it persists, that could make it harder for start-ups to raise money, he said.