Airbnb's valuation is set to rise to $13 billion, up from $10 billion earlier this year, as it prepares an employee stock sale, according to people familiar with its plans.



The valuation would make the accommodation site second only to Uber in the rankings of Silicon Valley's most valuable private companies, at a time when some venture capitalists are becoming concerned about the rate at which start-ups are spending capital.

Airbnb, which overhauled the design of its site and apps this summer, is without a chief financial officer after the departure of Andrew Swain last month, which may make an initial public offering unlikely in the near term.

To allow employees to cash in on some of their stock in the meantime, Airbnb is talking to its existing investors about allowing them to buy back tens of millions of dollars worth of shares, according to two people familiar with the situation.

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The funds would go to staff rather than raising new capital for the company, they said, and the terms are still being finalized. Airbnb declined to comment.

Momentum in private tech companies' valuations shows no sign of slowing despite recent gyrations on the public markets. Earlier this month, e-commerce company Square raised $150 million from investors at a valuation of $6 billion, which has doubled in two years.

Uber, whose offices are in the same building as Square in San Francisco, raised $1.2 billion in fresh capital at a $17 billion valuation this summer.

While few Silicon Valley investors will go as far as declaring that there is a another bubble in the tech world, some have begun to voice certain worries.