Bill Maris speaks during a conference in Laguna Beach, California on October 20, 2015.

Bill Maris, the former head of Google Ventures, is raising money for his own venture capital fund, according to people familiar with the matter.

Maris, who left Alphabet's start-up investing arm in August, has preliminary plans to raise between $350 million and $500 million, though no amount has been set, said the sources, who asked not to be named because his talks with investors are confidential.