Some prominent New York investors who had been bullish on the city and local start-ups have started to look beyond its borders. Fred Wilson, for example, a partner at the Manhattan firm Union Square Ventures, said he had been putting more money into other markets, including Europe and Canada.
In an email, Mr. Wilson defined it as a "gradual and nuanced change." He added, "I expect N.Y.C.-based companies will always be the largest cohort in our portfolio."
And investors are still betting on the city. The amount of venture, angel and private equity money invested in New York soared about 200 percent from 2009 to 2013, to $3 billion from $799 million, according to CB Insights, a data analysis firm that specializes in venture capital trends. Silicon Valley, by contrast, took in $11.4 billion in 2013.
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Anand Sanwal, chief executive of CB Insights, said New York showed promise in early-stage companies and that there were also opportunities to make the crucial mid-stage investments that companies need to grow and scale. He pointed out that New York now attracted more venture capital than Boston, which used to hold the runner-up title behind Silicon Valley.
"There are people who think New York is an irrelevant market," Mr. Sanwal said. "The more intellectually honest answer is that New York is just relatively immature. It's on a good path and it needs to run its course a bit more."
Among the local companies grabbing the attention of investors are Canary, which makes a smart-home security system; FiftyThree, which makes design apps for mobile devices; Kickstarter, the crowdfunding site; Warby Parker, the online eyeglasses retailer; MongoDB, a cloud services firm; AppNexus, an online advertising company; and Shapeways and MakerBot, 3-D printing start-ups.
Branch, a popular online conversation tool, was recently acquired by Facebook, and the shopping site Gilt is said to be preparing for its initial public offering. The online publishers BuzzFeed and Vox continue to grow, and Birchbox, a company that sells beauty products as a subscription service, announced that it had raised $60 million, valuing the company at close to $500 million.
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Entrepreneurs and investors agree that practically any tech company can be started in New York. The real challenge comes when trying to build a business with more than a five-person team working in cramped quarters and eating ramen, said Zach Sims, who started the coding instruction site Codecademy in Silicon Valley but moved it to New York, where he has hired 50 people in the last two years.
"The talent needed to grow a company to 500 people is a lot harder to find" in New York, he said.
That's because many of the city's most promising engineers go to work at outposts of major companies like Facebook, which offer big salaries and generous benefits. Facebook employs over 300 people in New York, 100 of whom are engineers. Google employs 3,600 people in the city, more than half of whom are engineers.