June 15 (Bloomberg) -- The Standard & Poor’s 500 Index may struggle to reach a so-called golden cross as trading volume decreases, according to a technical analyst at RBC Capital Markets.

The major stock indexes “are back above their 200-day averages, and it’s increasingly tempting to conclude that a new bull market is underway,” Toronto-based Ray Hanson wrote in a report dated June 12. However, the S&P 500 “has not yet achieved a golden cross” and “the steadily declining volume since early May suggests caution,” he said.

A golden cross, that’s considered a buy signal by analysts who make predictions based on patterns in price charts, occurs when the 50-day moving average, which is currently at 889.24 for the S&P 500, rises above the 200-day moving average, which is at 911.65, according to Bloomberg data. The U.S. benchmark index closed at 946.21 last week.

Moving averages show the average value of a security’s price over a set period and are commonly used to define areas of possible support, or floor, and resistance, or ceiling, in technical analysis.

The S&P 500 Index Volume, which shows volume in million of shares based on Bloomberg data, dropped to 758.15 on June 12, down 27 percent from May 1. The Nasdaq Composite Index, which closed at 1,858.8 last week, recorded a golden cross on June 5. Trading volume for the gauge was 0.6 percent higher that day compared with May 1.

To contact the reporters on this story: Francesca Cinelli in Milan at fcinelli@bloomberg.net.

Last Updated: June 15, 2009 08:10 EDT