It’s not easy being a high frequency trader these days.

Market volume is down and market volatility has largely vanished, making it ever harder for the high-speed trading crowd to employ their  blindingly quick and often repetitive “buy and sell” strategies on U.S. and European markets and reap a healthy profit.

And while the push for speed can be prohibitively expensive — with some signing up for the fastest possible fiber optic, microwave or chip technology — others see the beginning of the end of the high-speed advantage, as a growing universe of traders uniformly achieve the fastest speeds.

Combine that with heightened scrutiny by regulators in the U.S. and Europe and the possibility of new trading restrictions, and HFT traders have a lot of worries on their minds these days.

So what’s a competitive HFT trader to do?

For some, the answer has been to exit the market entirely. “We’re in the middle of a shakeout, where a lot of people have poured a lot of money into this [high frequency trading] and are now realizing that it’s not the gold mine they expected,” says Charles Jones, a professor of finance at the Columbia Business School and consultant to Citadel, a Chicago-based hedge fund, institutional trading firm and well-known practitioner of HFT strategies.

Jones says that he has seen a considerable number of small HFT firms — “two guys and a Bloomberg machine” — exit the scene or simply pare back their HFT efforts.

Larry Tabb, CEO and founder of research firm, TABB Group, is more specific: “Profitability for high frequency traders has been down fairly significantly for the last three or four years.”  His firm reports that HFT profits in U.S. equity markets dropped from $7.2 billion in 2009 to a projected $1.8 billion in 2012, while over the last two years, HFT as an overall percentage of U.S. equity volume has dropped slightly from 56 percent in 2010 to a projected 53 percent in 2012.

In the U.S., the activity has also been stifled by the pending Volcker Rule, which restricts commercial and investment banks from proprietary trading that does not directly benefit their customers. In November of 2011 Bank of America sold its high frequency trading operations to Getco, a major HFT firm.