PubMatic Investor Sues Over Ad Spend Hit to Revenue Forecast (1)

PubMatic Inc. hid from stockholders that its revenue tied to a top advertisement-buying partner was slipping as it shifted clients to a new platform, a proposed class action says.

The class proposed in the US District Court for the Northern District of California lawsuit filed Wednesday would include those who acquired PubMatic securities from Feb. 27, 2025, through Aug. 11, 2025, then watched them decline in value.

PubMatic connects ad buyers, so-called demand-side platforms or advertising agencies, with online publishers. PubMatic’s sell-side platform helps publishers manage ad inventory, the space they supply to advertisers. A DSP helps advertisers manage their ...