Ad-tech powerhouse AppNexus has raised an approximately $60 million dollar Series E investment round, allowing it to postpone going public as ad-tech stocks get pummeled.

The round, announced Monday, brings the company's total funding to $200 million and values it at $1.2 billion dollars. Another $40 million dollars may be on the way, the company said.

Markets have been unforgiving to ad-tech companies this year. YuMe, Tremor Video, RocketFuel and Millennial Media are each down at least 35% on the year. Recently public Rubicon is trading below its IPO price. And TubeMogul, which sought $93 million dollars in its IPO last month, walked away with only $44 million.

AppNexus CEO Brian O'Kelley said the market did not factor into the company's decision to raise its most recent round of funding.

"The truth is, I don't think market timing is possible," Mr. Kelley said in an interview with Ad Age. "It takes so long to go public that if we started now - if right now we're like 'Wow, crappy market, we're not going to go public,' by the time we would actually get public, the market could be fantastic."

The round gives the company added flexibility, he said. "What it really means is that we control our destiny. If we decide to be acquisitive, we can. If we want to invest internationally, we can. If we want to dramatically increase the size of our engineering team, we will."

AppNexus has never been shy about its aspirations to go public, but the timeframe for getting doing so is likely pushed back with the infusion of fresh capital. "I think it's still on the horizon," Mr. O'Kelley said.

He added that the company still has more than half the $75 million it raised in January 2013, and saw its first profitable quarter in Q2. The latest raise "is purely opportunistic for us," Mr. Kelley said.

AppNexus wouldn't name the lead investor on the round. "Their policy is not to disclose their name," Mr. O'Kelley said. The investor, which a spokesman described as a "Boston-based public equity and asset management company," is a new investor to the company. "With interest from other parties to invest up to an additional $40 million, the total potential investment is $100 million," the company said.