The second quarter was far from perfect, but there was still a lot of easy money for the big Wall Street firms.

    Goldman (GS), for instance, raked in $100 million in trading revenue in a single day 17 times during the second quarter, according to the firm's quarterly report. That compares with 6 at its rival Morgan Stanley (MS).

    The companies didn't make quite the killing they did in the first quarter, when Goldman and a few others posted positive trading revenue every single day, and Morgan Stanley reported losses on just 4 days. Both reported 11 trading-loss days in the second quarter.

    And the number of $100 million-plus trading-revenue days at Goldman fell by half in the latest quarter, from 35 in the first quarter. That is to say, the firm brought in at least $100 million every other day, on average, in that period – and just over once a week during the latest quarter.

    Of course, few will tear up at the news of a decline in big trading days for Goldman. For one thing, the firm told the Financial Crisis Inquiry Commission that as much as 35% of its revenue comes from businesses based on derivatives, the casino chips that played a role in deepening and spreading the financial crisis.

    Though execs at Goldman and elsewhere on Wall Street insist their trading gains don't entail taking on huge amounts of risk, the twists and turns of the past two years are making it hard not to be skeptical.