Sluggish markets and the May 6 flash crash pinched even trading highflier Goldman Sachs Group Inc in the second quarter, according to the company's quarterly report filed on Monday.

The New York-based investment bank reported 10 days of trading losses for the period, with three days of more than $100 million in trading losses, according to the filing.

Goldman's trading gains and losses have mirrored those of its Wall Street counterparts, whose surging first-quarter trading results cooled in the spring and early summer, as the S&P 500 Index <.SPX> shrank 12 percent during second quarter.

In the first quarter, Goldman hit trading perfection, reporting zero days of losses, or no trading days below $25 million in revenues.

While the second quarter was still largely profitable for Goldman's trading operations, the positive trading days oscillated between booming returns and sluggish results.

The bank reported 17 days with more than $100 million in trading revenues, followed closely by 12 days with revenues between $0 and $25 million.

Other Wall Street banks' results have largely followed the same trend, but their success has varied.

Morgan Stanley reported 11 days of trading losses in the second quarter, one day worse than Goldman. Bank of America Corp only reported one day with trading losses above $100 million, lower than Goldman's total.

(Reporting by Joe Rauch; Editing by Lisa Von Ahn)