Venture capitalists and corporate investors have poured nearly $28 billion into the ride services sector over the past decade, propelling growth at Lyft, China’s Didi Chuxing Technology, and Uber Technologies, according to a Reuters analysis.

Lyft has been working for about a year with Silicon Valley investment bank Qatalyst Partners, people familiar with the matter said. Lyft has used the firm to look at acquisition offers, investments, fundraising and partnership deals.

Founded by Frank Quattrone, Qatalyst is best known for helping technology companies find buyers. It had advised LinkedIn on its sale to Microsoft.

While it is not certain if Lyft will proceed with a deal, people familiar with the situation said General Motors and Didi Chuxing, which already have investments in Lyft, could expand their stakes in the San Francisco-based startup.

One Didi investor said any role the Chinese ride service played in a Lyft deal would likely be in coordination with a large automaker, rather than on its own. The investor did not want to be identified.

A Lyft spokeswoman declined to comment on whether any investment talks were going on, or on the relationship with Qatalyst, which was previously reported by the Wall Street Journal.

GM, the third-largest global automaker by vehicle sales, reaffirmed its commitment to expanding services with Lyft, but did not comment on potential future investments. GM invested $500 million in Lyft earlier this year.

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Didi has declined to comment. The company, which is battling Uber in the Chinese market, said in June that it had raised $7.3 billion in new funding, including $1 billion from Apple.

Investing in Ride Services

Lyft’s capital-raising efforts come as an array of deep-pocketed players—from big automakers to Saudi Arabia’s Public Investment Fund—are betting billions of dollars that selling transportation services a ride at a time will become a profitable, global business.

More than 70% of the $38 billion invested in all transportation-related startups during the past decade, including autonomous driving technology companies, has gone into ride services companies, according to the Reuters analysis of venture investments in more than 500 mobility-related startups over the past decade. The analysis was based on publicly available data on investments, as compiled by Crunchbase, CB Insights, and other sources, including the companies.

San Francisco-based Uber is valued at around $62.5 billion, Beijing-based Didi at around $25 billion, and Lyft at around $5.5 billion. By comparison, GM, which reported a record $9.7 billion profit in 2015, is valued at $43 billion.

Uber says it is profitable in the United States and Canada and about 100 cities globally, but is losing more than $1 billion a year in China.

Privately held Lyft is not profitable but is projecting $1.9 billion gross annual revenue based on bookings in May, according to a source familiar with the matter.

Initially, ride services startups relied on venture capital. Established automakers have recently put more of the cash they earned from booming vehicle sales into the ride services sector.

In addition to GM’s investment in Lyft, Volkswagen AG invested $300 million in Gett, and Toyota invested an undisclosed amount in Uber.

GM is working with Lyft to develop new services, such as a program called Express Drive, that allows drivers to rent a GM vehicle and use it to earn money providing rides.

The larger goal of the partnership is to use GM’s manufacturing prowess and Lyft’s network of more than 315,000 drivers to build a network of electric and eventually autonomous cars that generate revenue most of the day, instead of sitting idle in owners’ driveways.

GM President Dan Ammann last month outlined the strategy to tie together GM’s investment in Lyft and its acquisition of autonomous vehicle technology startup Cruise Automation, which industry sources estimate could cost up to $1.2 billion.

Ammann and Lyft President and Co-founder John Zimmer will appear together a technology event in Aspen, Colo., next month.

“We are making excellent progress in executing the key initiatives in our previously announced strategic alliance with Lyft, including implementing the Express Drive short-term vehicle rental program and working toward deploying autonomous vehicles into an on-demand network,” GM said in a statement.

Corporate investments in ride services and other mobility-related startups are likely to escalate, said Evangelos Simoudis, whose firm Synapse Partners advises large companies on how to adapt innovation strategies from entrepreneurs.

“Corporations recognize the high risk of being disrupted by technology startups,” Simoudis said. In turn, “Silicon Valley sees transportation as a stagnant industry in need of transformation.”