BENTONVILLE, United States — Just as the frenzy to fund technology startups at billion-dollar valuations was grinding to a halt last November, Fidelity Investments made one more bet.

The mutual fund led a $350 million round in e-commerce company Jet.com Inc. at what research firm CB Insights says was a $1.5 billion valuation. Now, with Wal-Mart Stores Inc. buying Jet.com for $3.3 billion, some of the biggest names on Wall Street and Silicon Valley — from Goldman Sachs Group Inc. to Google’s venture arm — are cashing in.

Jet.com’s backers may rake in anywhere from twice to 15 times their initial outlay, depending on when they invested. Latecomer Fidelity owned shares worth $14.6 million, according to a June 30 filing. While that investment hardly moves the needle for the giant investment firm — it represents just 0.079 percent of net assets in Fidelity’s Blue Chip Growth Fund — it is doubled in value in just eight months. A Fidelity spokesman declined to comment, citing a policy of not discussing individual investments.

Earlier investors will fare better. Those in the running for a five-times return include Alibaba Capital Partners, Citi Ventures, Coatue Management, Forerunner Ventures and General Catalyst. Also in that group are Goldman Sachs, Google Ventures, Norwest Venture Partners, Silicon Valley Bank, Temasek Holdings Pte and Thrive Capital. All of them invested in early 2015, according to CrunchBase, at what was reported to be a $600 million valuation.

But the biggest winners are investors from the first round in July 2014. At the time, Jet.com’s price tag was more than $200 million, a lofty valuation at the time considering it was an early funding round, according to one investor who participated. New Enterprise Associates led that round, with participation from Accel, Bain Capital Ventures, MentorTech Ventures, Primary Venture Partners and angel investor David Spector.

Those investors could pull in a 15-times return on their investment.

“It was an early round and I was lucky to get in," said Spector, who co-founded online lingerie startup ThirdLove. Spector said he believed in Jet.com founder Marc Lore, who had sold an earlier company that included Diapers.com to Amazon.com Inc. Most interesting to Spector was the new pricing mechanism Lore created with Jet, designed to decrease costs as shoppers added more items to their online cart.

Spector told other angel and venture investors about the startup but they passed, he said. Not only that, they began increasingly to needle him as Jet.com raised cash at higher valuations and announced plans to spend hundreds of millions on marketing to gain users.

“When I saw them socially, they’d give me an eye roll and a sarcastic ‘Hey, how’s Jet doing?” said Spector, noting that by then it had become unfashionable for startups to focus on anything but profit.

Spector has not worked out his actual return just yet because his investment was diluted with each subsequent round, but he considers it a win. “I got a few e-mails over the weekend, saying ’congratulations. You got the last laugh’.”

By Lizette Chapman; editors: Mark Milian, Edwin Chan and Robert Fenner.