Uber is growing—but so is U.S. rival Lyft.

Lyft is on track to complete 17 million rides this month, twice the amount of rides it did last October, Lyft co-founder and president John Zimmer said on Tuesday at a tech conference in Laguna Beach, Calif. hosted by the Wall Street Journal. That’s a steady increase from the 13.9 million it completed in July, according to a memo to investors that was leaked.

Zimmer also said that Lyft’s market share has grown over the past two years, and the company currently provides roughly one in four to one in five rides in major U.S. cities, on par with a recent report from mobile data analytics company 7Park, which says it has grown from 9% to 20% market share over that period.

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Still, it has ways to go compared to Uber, which now has 40 million monthly riders globally, CEO Travis Kalanick said last week. In July, Uber said that it completed 62 million rides in the U.S.—more than four times as many as Lyft. Meanwhile, Didi Chuxing, which agreed to acquire Uber’s Chinese business in August and is an investor in Lyft, is doing 20 million rides per day, president Jean Liu said during the Journal‘s conference on Tuesday.

And like all its peers and competitors, Lyft is subsidizing a lot of this growth—to the tune of a reported $50 million per month (or as Zimmer once described it, “investing” into the business).

Zimmer also insisted that Lyft is not for sale, contrary to recent rumors which mischaracterized the interest it received, and that it’s taking its time to consider going public.

“We’re four years old as a business,” said Zimmer. “We’re in no rush to go public, we don’t need to. We get offered new capital every few months,” he said, adding that an IPO “is something we are likely to do in the future.”

But the biggest mystery remains the future of Lyft’s logo—the signature pink mustache it’s had since the beginning. Zimmer said the mustache may go away later this year, but declined to share more about the company’s next logo.