Advertising exchange PubMatic has filed a lawsuit against Google, accusing the tech giant of illegally monopolizing the ad technology market. PubMatic is seeking billions of dollars in damages, according a report from Bloomberg.

The lawsuit marks the second time that an advertising exchange has sued Google since a federal judge ruled in April that the search giant had illegally monopolized ad exchanges and ad servers. The judge has set another trial for this month to determine whether Google should be forced to sell off parts of its advertising business due to its illegal conduct.

PubMatic CEO Rajeev Goel says his company’s lawsuit isn’t just about money, but about ensuring that online advertising markets work.

“It felt like for many years no matter how well we innovated there was a barrier holding us back,” Goel told Bloomberg. “That barrier wasn’t the limits of our technology. It was Google’s illegal monopoly. Every time we adapted or innovated, Google found new ways to stack the deck.”

PubMatic works with websites to sell advertising, competing directly with the Google Ad Manager (formerly DoubleClick). According to testimony from Google’s antitrust trial last year, the company considered buying PubMatic in 2011, but ended up purchasing advertising technology provider AdMeld instead.