(tumblr.com)

Local blogging platform Tumblr has raised a staggering $125 million in venture capital. Tumblr is now hosting more than 53 million blogs with images, video and a complex system of duplication via reblogs, all for free, so the company needs the cash. "In about six months, the word 'Tumblr' will eclipse 'blog' in Google popularity," wrote the web comic artist and statistician Randall Munroe of XKCD.

Welcome to the big leagues. And at its size, Tumblr's investors are keeping a closer eye on the goings-on at the wildly unprofitable startup. After years of leaving Tumblr's magical fairyland largely to its own devices, two recent major changes suggest the company may be feeling pressure from investors (and its burn rate).

John Maloney previously ran the forum for Upper East Side moms UrbanBaby, where he employed David Karp. Four years ago, Mr. Karp then hired Mr. Maloney to serve as president and resident adult of Tumblr. Last week—late on a Friday, naturally—Mr. Maloney announced he is stepping down from the company.

"I told the team and board this week that it’s time for me to transition away from running day-to-day operations. It’s the right time for me and a good time for Tumblr. We’re in great hands with David and the excellent leadership team we’ve built. The company is filled with amazing people," Mr. Maloney wrote obliquely on his personal Tumblr.

He will spend more time with family and "learn a bunch of new things," he wrote.

The news of Mr. Maloney's resignation comes after Mr. Karp announced that Tumblr will start selling a form of advertising this week--a revenue option the founder had hoped to avoid. The words of early Tumblr investor Fred Seibert in late 2010 ring prescient: "You're going to have to prove to somebody that you're really worth the money they gave you," he told Mr. Karp at the time.

To its credit, Tumblr has fixed the downtime issues that plagued the service for months and its controversial fashion director Rich Tong is now gone. But the popular blogging service, which has more than half the users MySpace did at its peak, has yet to prove it's worth the money investors gave it.

"One could guess from these developments, and their open-ended question marks, that Tumblr's board has finally decided to start calling shots," a source Gchatted Betabeat over the weekend.

Mr. Maloney did not immediately respond to a request for comment.