said on Wednesday that users under 25 spend more than 32 minutes a day on Instagram, demonstrating its success with an age group that Snap also targets. Snap released similar data at the beginning of February, noting that "users younger than 25 visited Snapchat over 20 times and spent over 30 minutes on Snapchat every day on average."
Despite record highs in the broader market, Snap shares have fallen about 43 percent in the past three months, and on Wednesday shares were more than 4 percent lower at one point, hitting an all-time low of $12.52 a share.
The fresh reminder of Instagram's competitive position comes amid a tenuous time for Snap's stock.
Snap's lockup period is expiring, allowing company insiders and early investors to unleash their shares into the market. Regulatory filings show that no major insiders have sold shares so far this week, although several have shuffled around their shares, presumably as stock options vested.
Still, it's common for share prices to fall around this period as investors wait to see if top executives sell shares. MKM derivatives strategist Jim Strugger said that over the month preceding the lockup expirations of Facebook, Twitter and LinkedIn their stocks were down by an average of 24 percent, about the same as Snap's decline over the last month.
On top of that, S&P Dow Jones Indices dealt a blow to the company this week. S&P Dow Jones said it will bar stocks that issue multiple classes of shares from some indexes, effectively excluding Snap, which offers no voting rights to common shareholders. By forgoing an S&P 500 listing, Snap could miss out on a growing pool of wealth, as more investors opt for index funds over active fund managers.
Snap will get a chance to prove investors wrong in its quarterly earnings report this month, when Wall Street analysts say they will look for signs that Snap's user growth is accelerating even as Instagram has users hooked.
Analyst Mark Mahaney of RBC Capital Markets told "Squawk Box" on Monday that competition is "the single biggest risk" for Snap.
"It's a very hard thing to predict. We do like, though, the ongoing ... innovations that we're seeing in Snapchat. I thought Snap Maps was one of the more interesting features that we've seen in the space for a while. They have to continue to do that, and this team seems to have a pretty good track record so far; the stock should work," Mahaney said.
— CNBC's Thomas Franck contributed to this report.