(Bloomberg) -- Snapchat’s valuation was cut by 2% in December by one of its largest investors. This was Fidelity Investments’ second writedown of the photo-sharing app maker in three months.

Mutual funds have recently marked down the values of their stakes in several private technology companies, including Dropbox and Zenefits. The moves are another jolt of sobriety for Silicon Valley startups as they face a tighter fundraising environment.

The Fidelity Blue Chip Growth Fund, one of the funds that holds Snapchat, reported the value of its Snapchat shares at $17 million as of Dec. 31, according to a public filing. The same holding had been valued at $17.4 million on Nov. 30.

Snapchat raised money at a $16 billion valuation last year, people familiar with the matter said at the time. Fidelity bought convertible preferred stock in March. “We are confident in our business,” said Mary Ritti, a spokeswoman for Snapchat.

Snapchat, which people use to send disappearing photos and videos, has more than 100 million users. Media brands, including Walt Disney's ESPN, Time’s People magazine and BuzzFeed, use the service to share short videos and articles.

Snapchat mainly makes money by selling ads on those channels and within its curated video pieces about live events, called Snapchat Stories. Snapchat has more than 7 billion video views a day, people with knowledge of the matter said last month.

To reevaluate private stocks, Fidelity has a committee that meets regularly and decides what the shares could be reasonably sold for. The information is based on what it knows about the company and what’s happening with peers that are publicly traded.

Shares in Twitter, another social networking company like Snapchat, have been cut in half since the beginning of last year. Fidelity had previously marked up its Snapchat stock during some periods last year. Fidelity declined to comment on how it calculates the value of any specific holding.

“While the dollar amounts of each individual investment can be large, these holdings are very small positions within any given fund,” Fidelity said in a statement. “We have a rigorous and thorough valuation process for mutual fund holdings.”

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