From Her First $100K to 3 Million Followers

By comparison, putting $500 in a popular portfolio at the roboadviser Betterment costs just $1.25 a year (0.25 percent of the money invested, plus a tad more for the underlying investments). Ellevest, a roboadviser geared toward women, charges $12 annually for its most basic investment plan, and includes extras like online workshops and email courses from certified financial planners.

“There are cheaper options, and yet so many people just don’t invest, period,” said Treasury’s chief executive, Elias Rothblatt, who founded the service with Ivar Vong.

He said Treasury’s goal was to give users the nudge they needed to get started. “If you put $50 or $100 into a low-cost investment and that makes you feel like, ‘Oh, cool, I learned about investing,’ then that is a major win,” he said.

The service, which became available to the public in January, has drawn 2,000 users who have invested nearly $13.5 million. In 2021, it helped people invest $4 million of that during its private beta testing. More seasoned investors also see the appeal: Start-up funders, led by Bloomberg Beta, have put in more than $1.25 million.

Nearly 270 people took part in that February session. Ms. Dunlap started with a pep talk before diving into explanations dotted with metaphor. She likened buying shares of Amazon, for example, to “owning a grain of sand on Bezos’ beach.”

A little blue counter ticked away in the corner of the screen, tracking total dollars invested as participants made purchases, buying shares of investments like the Vanguard Total World Stock E.T.F., State Street’s Global Diversity Index E.T.F. and more. More than half bought something in that hour, spending roughly $120 each — a modest sum, but a meaningful first step.

“This is not TJ Maxx’s candle aisle,” Ms. Dunlap joked as trades piled up in the chat stream. “Please make smart choices.”