Traders work on the floor of the New York Stock Exchange. Photo: Reuters/Brendan McDermid

S&P 500 companies that have reported positive Q2 earnings surprises so far have seen an average price decline of 0.3%, reports FactSet. It is the first such drop since Q2 in 2011. The decrease cited is from each firm’s price two days before reporting earnings and two days after.

The performance compares to the average increase in price for upside earnings surprises of 1.4% over the past five years.

It is unclear what is driving the trend, but it is not likely due to EPS guidance or Q3 revisions. More S&P 500 firms have issued positive EPS guidance for Q3 2017 than average.