The capital crisis for venture-backed start-ups continues, according to the quarterly exit-poll report by Thomson Reuters and the National Venture Capital Association, released Wednesday.

In the third quarter, only one venture-backed company, Rackspace Hosting, went public. Its shares are down 15 percent since then. A biotech company, Fluidigm, came close but withdrew its registration in the wake of the meltdown on Wall Street. In the first three quarters of 2008, only six technology and health care start-ups have gone public, the lowest volume since 1977. At this point last year, 55 had staged I.P.O.s.

Acquisitions, the other method for investors to cash out of start-ups, are only slightly better. Fifty-eight venture-backed companies were sold in the third quarter, compared with 102 in the same period last year. The quality of those deals also fell. The average deal size in the third quarter of this year was $146 million, compared with $208 million last year.

Venture capital is, in some ways, protected from the credit crisis and turmoil in the stock markets because venture investments are long-term — the life of a venture fund is a decade — and venture firms and start-ups do not rely on the availability of debt.

However, as the results this quarter illustrate, the financial crisis will only hurt exit markets, which have been tightening for the last year.

If the pattern continues, it could have devastating effects on the venture ecosystem. If venture capitalists cannot cash out of their investments and write checks to their investors, those investors could stop putting their money in venture funds. And if venture firms are forced to continue to spend money and time on older companies that they expected to exit from their portfolios by now, they will not be able to finance new start-ups.