Two-of-three companies on Standard & Poor’s 500 roster have exceeded analysts’ per-share expectations consistently since the first quarter of 2004, suggesting companies are extremely conservative in their earnings guidance to analysts and then over-deliver on results. That’s according to a study by Chicago-based Parson Consulting of earnings-per-share projections and actual earnings results.

Noting that nearly one in four S&P 500 companies have beaten analysts’ expectations by more than 10 percent, Parson said the findings imply that companies have become more conservative in their earnings guidance following the passage of Sarbanes-Oxley.