With 23 Grand Slam titles and an estimated $225 million fortune, Serena Williams has dominated the tennis world for some time. Lately, she’s been working on ways to parlay her brand--and her 30-odd million social media followers--into new wins. In 2018, she launched fashion line S by Serena and patented cosmetics brand Aneres. Perhaps most impressively, the sports icon has quietly scattered an estimated $6 million in investments across more than 30 startups over the past five years. Five of her investments are reportedly up at least five-fold, and the value of her portfolio has reportedly doubled to more than $10 million. In April, Williams and former JPMorgan asset manager Alison Rapaport announced the launch of her eponymous fund, Serena Ventures. The vision: to support (and generate returns from) startups run by women and people of color. Its portfolio includes women’s co-working space the Wing, sculptwear startup Honeylove, and kids clothing site Rockets of Awesome. --Zoë Henry

Michelle Larivee, co-founder of health and wellness company WTHN, turned to acupuncture for a couple reasons: to ease her back pain following a ski accident, and to help her get pregnant. "I always say I have two babies at the same time, my acupuncture baby, and my son, Sam," says Larivee. "I mean, this for me was just truly transformative." The former investment banker and consultant opened an acupuncture studio in New York City in 2018 that became profitable after just three months. This year the company, which has raised $2.5 million, launched a selection of blended herbs with names such as Dream On for sleep, and Can't Touch This for an immune system boost. Larivee says the company should hit $2 million in revenue this year. She’s planning more studios in New York and is looking to expand to cities such as Boston, San Francisco, and Washington, D.C. --Brit Morse

Many people with diabetes have nerve damage in their feet, which prevents them from feeling injuries that can become infected and lead to amputations. Siren’s flagship product, launched last year, is socks with embedded sensors that detect temperature increases, a sign of inflammation. That data is transmitted via an app on the wearer’s phone to health care providers. The socks are machine-washable and look and feel like regular socks, co-founder Ran Ma says. Patients get five new pairs every six months; insurers cover the cost, because the socks prevent even costlier medical complications. In December, the San Francisco company published peer-reviewed research on the socks’ effectiveness. “I’ve had people tell me feet aren’t sexy,” Ma says. “Diabetes isn’t sexy. The elderly are not sexy.” But she’s pushing ahead, armed with more than $10 million in funding. She adds: “My definition of sexy is creating a profitable business and saving lives.” --Sophie Downes

Not many entrepreneurs have to rent out convention centers to celebrate their companies’ silver anniversaries. But that’s what Judi Sheppard Missett did in June, when more than 3,000 teachers and students of Jazzercise descended on San Diego for two days of classes (some taught by the 75-year old Missett), branded apparel, and general hoopla. An on-site museum chronicled Missett’s odyssey from a 13-year-old hoofer instructing kids in her parents’ basement in Iowa through her founding of an international brand that was, in the ’80s, the nation’s second largest franchiser and a pioneer in the fitness industry. Today, Missett remains CEO of the $100 million company, with more than 8,500 franchises worldwide. (Her daughter, Shanna Missett Nelson, is president.) “There aren’t a lot of women who started a company and are still running it 50 years later—and that company is thriving,” says Missett. --Leigh Buchanan

It’s safe to say that Brynn Putnam, a former professional ballerina and the founder of Refine, a group of three fitness clubs in New York City, knows a thing or two about exercise. But, after having a baby, she found herself in an unthinkable position: she was a gym owner with no time to go to the gym. Putnam also noticed her Refine members loved it when she installed more mirrors, something Putnam had been used to as a ballerina. Putnam hooked up a Raspberry Pi computer to a mirror to create a hacked-together mirror-slash-fitness instructor. Many iterations later, that product became Mirror, which streams fitness classes and is second only to Peloton as the breakout fitness product of the pandemic. Retailing at $1,495 plus subscription fees of $39 a month for on-demand classes, Mirror is not for everyone. In July, though, Lululemon decided it definitely was for them, and purchased the company for $500 million. –Gabrielle Bienasz