Reddit founder Alexis Ohanian has $225 million in fresh funding to back early-stage start-ups through his venture capital firm, Initialized Capital.

The firm, co-founded by Ohanian and Garry Tan, announced Tuesday the closing of its fourth fund. It now manages more than $500 million and counts more than 100 portfolio companies. The firm has made investments in heavyweight start-ups such as real estate platform Opendoor, grocery delivery start-up Instacart and digital coin trader Coinbase.

"We have a model that works," Ohanian told CNBC in an interview. "The last fund — fund three — was kicking off a vision to create a firm that could really be as founder-focused a platform as possible, serve founders as well as possible and, in a lot of ways, to be the partners that Garry and I wish we had."

The firm looks at companies in every sector, but it is seeing standouts in the health tech and elder tech spaces, Ohanian said. Initialized is partnered with Roman, a digital erectile dysfunction company prescription platform, and online pharmacy TruePill.

Initialized closed its third fund in 2016 with $115 million and only one of the founders on full-time. Ohanian was still running Reddit, so Tan ran the firm. Ohanian left the social platform earlier this year.

Initialized prides itself on being "the first check to folks when they first quit their jobs," Tan told CNBC. "As a venture capitalist it's more important than ever to go back and focus on the believers and designers."

Early stage financing is gaining importance as tech companies increasingly delay IPOs and the sector becomes increasingly consolidated at the top, Tan said.

Initialized is unlocking a lot of late-adopter industries, he said. The saying "If your business isn't broken, don't fix it" doesn't apply anymore, he said. "Amazon is coming for all of it."