There has been no New Year’s bounce, says Raymond James Equity Research. Trading in stocks in the United States in the first half of January is down 18% versus a year ago.

Trading has picked up 5% from what analyst Patrick O’Shaughnessy called “an exceptionally slow December.”

But , “it appears investors and traders are in wait-and-see mode,’’ he said, in a report to clients. “A slow start to the year will reinforce expectations that trading volumes are likely to be relatively depressed in 2012 as economic uncertainties in the U.S. and Europe persist, the regulatory environment remains cloudy, and dealer banks continue to re-evaluate their business models and reduce headcount. “

January is “on pace to be the second lightest month” in the last four years for stock trading in the United States. The only lighter month? Last month, i.e. December 2011, with an average daily volume of 6.4 billion shares.

In the previous two years, trading volume had big New Year’s bounces, jumping 23% in January 2010 and 21% in January 2011. U.S. equity option volumes were up 36% and 37% over the last two Januarys.

The big exchanges lost share in the first half of January, Raymond James reported.

The New York Stock Exchange’s average market share stood at 23.7% in January versus 25.5% in December, while the Nasdaq Stock Market’s average market share stood at 20.2% versus 20.7% in December.

Off-exchange trading in dark pools represented 34.5% of total U.S. equities volumes during the first half of January, O’Shaughnessy said. That, the anlays said, is “continuing a shift back toward off-exchange volumes following the August-September spike in market volatility.”

The CBOE Volatility Index (VIX) continues to fall, Raymond James noted, averaging 21.3 in the first half of January versus 25.0 in December and 36.5 in September 2011.

Tom Steinert-Threlkeld writes for Securities Technology Monitor.