“The general sentiment in Silicon Valley is that we’re not yet there, but the reality is that we are,” Mr. Swildens said. “It’s already started.”

The region feels as if it is on the cusp of a mood shift. On the one hand, its denizens say they feel fortunate to be working in a segment of the economy and living in a region that has been hurt far less than other parts of the country. They also express stubborn confidence in the inexorable shift to the Internet and the role that Valley technology companies will play in that transition.

And they assert that they are not feeling anything like the pain that followed the collapse of the dot-com bubble, which led to big job losses, an exodus of talent, a plunging commercial real estate market and a significant drop in investment in start-up companies.

But having assiduously clawed its way back from the dot-com bust, the Valley is again facing some tough conditions. At the area’s blue chip companies, stock performance has turned grim as growth has slowed. Google’s stock has fallen around 31 percent this year; Apple is down 21 percent. The Nasdaq composite, an index with a major technology focus, is down 11.4 percent this year.

Among the shares of venture-backed companies that went public in the last year, only 28 percent are above the offering price. That compares with around 50 percent in a typical year and 70 percent in strong market conditions, according to the National Venture Capital Association.

New companies are hitting roadblocks on their way to the capital markets. Upek, a company in Emeryville, Calif., that makes computer chips and software used for fingerprint recognition, registered to go public last May. It then began trying to drum up investor enthusiasm, and was making progress. But on March 4, it withdrew its registration.

Image Credit... The New York Times

On Wall Street “there was suddenly no more appetite for growth companies,” said Eric Buatois, a general partner in Sofinnova Ventures, an early-stage investment firm that backed the start-up.