NEW YORK (AFP) - Global banks are past the worst of their crisis over their securities activities, a top rating agency said Thursday referring indirectly to such toxic assets as subprime mortgages. The assessment should underpin the credit ratings of affected banks, the credit rating agency Standard & Poors said, but improvement in their securities-related businesses would be gradual. And it noted that in a separate area of banking activity, losses from bad loans were now rising. Our belief that these issuers securities-related businesses have bottomed out should help to relieve downward pressure on their ratings, S&P credit analyst Scott Sprinzen said. But he warned: However, we anticipate that, in some cases, escalating credit losses will more than offset any benefits from improving securities-related results. The agency said that although US banks in almost every major market were feeling the severe effects of weak economic activity and their own mounting credit losses, it held that global banks securities-related businesses have already seen the worst. The economic downturn had hit banks securities business first and on several fronts. Among the problem areas were asset-backed securities, collateralized debt obligations, residential mortgaged-backed securities, and monoline-related and leveraged finance positions. The results of global banks had also been cut back by a drastic slowing of activity from the middle of 2007 and which had accelerated until late in 2008. However, we now think that fourth-quarter 2008 likely marked the trough for these banks trading operations and that first-quarter 2009 has seen the bottom of their investment banking, asset management, and wealth management businesses.