Lyft on Friday said that heavyweight investor Carl Icahn has pumped $100 million into the ride-sharing startup whose rivals include Uber.

Icahn Enterprises led a $150 million funding round that gave Lyft an estimated market value about $2.5 billion.

"We are very happy to be investing in Lyft," Icahn said in a release.

"I believe that ride-sharing is poised to become a fundamental component of our transportation infrastructure."

Icahn added that Lyft revenue has been rising, and that the growth in cities in the coming decade promised to drive demand for the ride-sharing service.

"We're thrilled to partner with Carl during this exciting period in Lyft's growth as we work to rebuild the US transportation infrastructure and reconnect local communities," Lyft president John Zimmer said in a release.

"With this additional investment, we remain focused on deepening our US footprint, continuing to lead with product innovation and providing the best possible experience for drivers and passengers."

Lyft said in March it raised $530 million in a funding round led by Japanese ecommerce giant Rakuten to fuel expansion in the US and abroad.

Startups in the "on-demand" sector -- such as Uber and Instacart, which offer speedy services on a smartphone app -- are seeing an unprecedented surge in venture capital, a new report showed Thursday.

Funding for on-demand companies jumped 514 percent last year to $4.12 billion, and new investments in early 2015 have totaled at least $3.78 billion, according to venture capital research firm CB Insights.

Icahn, a billionaire activist investor, has earned a reputation by taking stakes in companies such as to press for changes including measures to boost value for shareholders. In the tech sector, those firms have included Apple, eBay and Yahoo in recent years.