A derivative lawsuit filed in Delaware federal court Monday accused TrueCar Inc. of failing to warn investors about changes to its co-branded car-selling website with USAA, which allegedly caused the company to lose hundreds of millions of dollars in market capitalization last year.

According to the complaint, Santa Monica, California-based TrueCar, which operates an internet-based platform for car pricing, disclosed the possibility of changes as merely a risk to its bottom line for nearly a year, when in fact it knew that they were already underway.