For years Roy Soifer has been tracking what he called the Harvard MBA Indicator: the share of new Harvard Business School graduates who go into “market sensitive” jobs like investment banking. If you see a huge influx of elite students into these fields, the story goes, that may be the sign of a bubble.

Finance, consulting and tech still dominate the career choices of Harvard MBAs, but lately a new area is starting to look bubbly too: entrepreneurship. The last three years, 7 percent of newly graduating students decided to launch their own businesses at graduation, compared to 4 percent about five years ago. It’s not quite as high as the 11 percent during the dot-com bubble, but still a steady increase.

The entrepreneurship boom is even more pronounced at other schools. At Stanford, about 1 in 5 members of the Graduate School of Business class of 2013 said they were starting their own business rather than seeking employment at an existing firm. That’s the highest share on record, according to my conversations with professors and administrators there.

“It’s built from about 3% back in 1990 to that number, with big bumps up to 10-12% during the late 1990s era, a drop-off after that, and a steady rise over the last few years,” Paul Oyer, an economics professor at Stanford’s Graduate School of Business who has studied career trajectories of MBAs, told me.

Here are the exact numbers I was able to track down:

No data available for 1990-2004.
No data available for 1990-2004, but I’m told that the rate was around 10-12% during the dot-com bubble.

M.I.T.’s Sloan School of Business, which posts most of its employment data online, shows a similar trend:

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And here’s Wharton:

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I should mention that we’re not seeing rising entrepreneurship at every business school. A few top schools (like Columbia Business School and the University of Chicago’s Booth School of Business, both finance strongholds) still send only a tiny share of new grads into entrepreneurship. And across business schools overall, entrepreneurship rates have flatlined around 4 percent to 5 percent for about the last decade, according to the Graduate Management Admission Council’s annual survey data, with the chances of founding a new company rising the longer alumni have been out of school.

What seems to be changing is that alumni of a handful of elite schools are striking out on their own much earlier today than in days past. It’s not clear why this is happening, or how sustainable the trend is. New ventures are very risky, after all, and student loans are expensive. But for now, elite b-school grads seem unusually eager to start their own businesses. The same is not true of Americans overall, at least if you look at employer firms.

Catherine Rampell is an opinion columnist at The Washington Post.