Ride-hailing start-up Lyft has raised a new $500 million round of funding, a source told CNBC, bolstering its valuation to about $7.5 billion, postmoney, as rival Uber faces scrutiny.

Lyft was last valued at $5.5 billion in 2015, according to researchers at CB Insights. Some details of the funding round were previously reported by the Financial Times and The Wall Street Journal.