Online advertising firm Clickable closed a $12m series C financing round yesterday, led by financial services firm American Express with participation from venture capital (VC) firms Union Square Ventures, Founders Fund, and private equity firm FirstMark Capital.
Founders Fund, Union Square and FirstMark were investors in Clickable’s $14.5m series B round in July 2008. Union Square, FirstMark, under its prior moniker of Pequot Ventures, and managing partner of Founders Fund Peter Thiel were among the participants in Clickable’s series A…