Confidence levels among venture capitalists in Silicon Valley have also plummeted, as the credit crisis shows no signs of abating.

"The financial markets crisis is causing venture-backed companies to postpone or shelve their plans to go public, said NVCA President Mark Heesen. The NVCA is the venture capital industry's largest trade group, with nearly 500 members.

So far this year, only six venture capital-backed companies have gone public. Another 28 such companies have withdrawn their registration statements for an initial public offering of securities, the survey said.

"The ripple effects of the public market crisis are already being felt in the private markets," said Jessica Canning of Dow Jones VentureSource, which released its quarterly survey on Tuesday."