Correction: This article has been updated to fix the ticker symbol for Rubicon Project and correct its stock activity.

NEW YORK (TheStreet) -- Sometimes it's better to be discreet.

Advertising technology seemed like such a good business a couple of years ago. Marketers were moving more money to digital platforms, heightening the need for sophisticated programs to help them target their spending.

But things haven't worked out as planned. Ad-tech stocks are mostly in free-fall, torn asunder by questions about their efficacy, ability to withstand fraud and more recently, the surge of interest in ad-blocking apps.

"The public market is not supporting ad-tech right now," Erich Wasserman, co-founder of the private firm MediaMath, which develops analytical software to root out customers on the web and pair them with marketers, said in an interview. "The fragmentation - of both the online experience and the industry in general - isn't going anywhere."

Public companies in the space have taken a beating over the past year: Tremor Video (TRMR)  is down 18% from $2.32 to $1.90. YuMe (YUME) has fallen 42%, Rocket Fuel (FUEL) has lost 70%. Los Angeles-based Rubicon Project (RUBI) - Get Report is a major exception to the trend, up 41% since a year ago to $14.96 from $10.64.

That's why MediaMath, which received $73.5 million in Series C funding from Boston-based Spring Lake Equity Partners in June, is happy to stay private -- at least for the time being. MediaMath added 300 employees in 2014 and moved into a spacious office this week in lower Manhattan.

"The private marketplace is offering us plenty of access to capital," said Wasserman. "We like that we're developing where we are."

With multiple headwinds blowing in the face of the ad-tech business, the shelter of private capital does indeed look warm and cozy. Both public and private companies within the space have to contend with competition from megaliths Google (GOOG) - Get Report and Facebook (FB) - Get Report , who have their own ad-tech services and a lot more money to throw around than their smaller counterparts.

There's also the threat of ad-blocking software, which can switch off online advertisements altogether. Apple's (AAPL) - Get Report new operating system iOS9, which launched in September, allows users to block ads on their iPhones and iPads for the first time - a move than sent shockwaves through the ad-tech space.

Wasserman downplays the threat, however, calling its impact on revenues "negligible."

"The major marketers out there are not interested in being beholden to three players," he said, referring to Apple, Google and Facebook. "Programmatic ads will not be going away."

Still, MediaMath is feeling pressure to hunker down for the long haul, while the ad-tech space shakes off its early-days volatility.

"We've been managing the business to maintain control of our product, not simply to gain top-line growth," said Dan Rosenberg, the company's vice president of corporate development, over the phone. "We knew it was going to be a slog."