Tennis star Serena Williams says she is retiring from tennis.

Williams announced the news in a Vogue articled published on Tuesday morning that she co-wrote with writer Rob Haskell.

Williams is one of the greatest athletes of all time. She has won 23 Grand Slam singles titles — the most of any man or woman in the Open Era, which began in 1968.

She is now 40 years old and has battled various injuries in recent years, so retirement seemed like it might come soon. But Williams didn’t talk about it openly until the Vogue issue came out.

“I have never liked the word retirement,” Williams says in the article. “Maybe the best word to describe what I’m up to is evolution. I’m here to tell you that I’m evolving away from tennis, toward other things that are important to me.”

Williams is married to Reddit co-founder and executive chairman Alexis Ohanian, and has a 4-year-old daughter with Ohanian. In the article, Williams says after she retires she’ll focus on spending time with her family and working with her venture-capital firm Serena Ventures.

Williams has a net worth of approximately $260 million, according to Forbes estimates, and made $45.3 million last year. Nearly all of her earnings have come off the tennis court in recent years — she has sponsorship deals with brands like Nike NKE, AT&T T and Gatorade. Some predict she will be the first female athlete to become a billionaire.

And she has made it a priority to invest in other women.

In the Vogue article, Williams says that a few years ago she watched a talk between JPMorgan Chase JPM CEO Jamie Dimon and Caryn Seidman-Becker, the CEO of the security company Clear. “Caryn explained that less than 2 percent of all VC money went to women. I figured that she misspoke. I thought, There’s no way that 98 percent of that capital is going to men. I approached her afterward, and she confirmed it.”

Williams said it made her understand that “someone who looks like me needs to start writing the big checks. Sometimes like attracts like. Men are writing those big checks to one another, and in order for us to change that, more people who look like me need to be in that position, giving money back to themselves.”

Williams indicated that she will still play in August’s U.S. Open in New York City, a tournament Williams has won as a singles player six times.