Commercial real estate can be a lucrative investment, but it can be hard to come up with the money to buy a stake in the first place.

That’s the idea behind RealtyShares, a platform which pools together debt and equity investments for apartments, office buildings and retail centers.

Now the San Francisco-based startup has gained enough traction to find another big investment for itself. RealtyShares is raising a $28 million Series C round led by Cross Creek Advisors, with participation existing investors including Union Square Ventures, General Catalyst Partners, and Menlo Ventures.

Founder and CEO Nav Athwal says that RealtyShares has over 120,000 users on the platform. The startup says it has deployed over $500 million across more than 1,000 properties since it was founded in 2013.

RealtyShares aims to “diversify in the real estate in a way that hasn’t been possible before,” said Athwal. He said that the typical transaction is between $2 million and $50 million.

Although once…