Santa Barbara-based QFour Digital, a new firm focused on acquiring and operating companies in the online advertising and marketing industry, received an investment earlier this week from GTCR, a private equity firm. QFour will be headed by former ValueClick COO and Commission Junction CEO Jeffrey Pullen. Financial terms of the investment were not disclosed. GTCR Golder Rauner LLC is a private equity firm managing over $8B in equity. GTCR said the investment will come out of GTCR Fund IX LP, a $2.75B private equity fund.