As part of its efforts to grow its fleet of autonomous robo-taxis and expand into new cities, Waymo has raised $5.6 billion from outside investors, its largest funding round to date .

Waymo’s parent company, Alphabet, led the round, which included investments from Andreessen Horowitz, Fidelity, Perry Creek, Silver Lake, Tiger Global and T Rowe Price, according to a release.

The new money is responsible for Waymo’s first taste of commercial success. Its robot taxis now make more than 100,000 trips each week in San Francisco, Phoenix and Los Angeles, double that number in May, and will operate in Austin, Texas and Atlanta by 2025 through a partnership with Uber .

Waymo has already raised outside investment twice — $2.25 billion in 2020 and $2.5 billion in 2021. The most recent round was oversubscribed, the company said, and it did not disclose the valuation of Waymo nor the part of the cycle that Alphabet represented. During an earnings conference call in July, Alphabet executives said the company planned to invest an additional $5 billion in Waymo over the coming years.

Cycle investors “are not looking for a quick turnaround in their money,” said Chris Ballard, managing director of Check Capital Management, an investment firm. “These are long-term businesses that want to achieve much greater results over a much longer period of time.”

The company has many competitors, including Tesla and its recently unveiled robot taxis, Amazon’s Zoox and General Motors’ Cruise service. Waymo isn’t profitable yet, but right now it has the largest number of autonomous robo-taxis actively on the road.

Its current fleet of vehicles consists of electric Jaguar I-Paces, but Waymo this month announced a partnership with Hyundai and began testing its vehicles made by Zeekr, a Chinese electric automaker, in July. NYTIME