April 14 (Bloomberg) -- Goldman Sachs Group Inc. headed for the biggest decline in almost two months in New York trading after Standard & Poor’s said the bank’s better-than-estimated earnings may not be sustainable.

First-quarter profit of $1.81 billion was concentrated in Goldman Sachs’s fixed-income trading business, the rating company said in a report today. S&P left in place its negative outlook on the New York-based firm’s credit rating of A.

“Coupled with persisting weak economic conditions and capital markets turmoil, we believe it would be premature to conclude that a sustained turnaround” in Goldman Sach’s financial performance is under way, S&P wrote.

Goldman Sachs fell 9.6 percent to $117.65 at 2:54 p.m. in New York Stock Exchange composite trading, the biggest decline since Feb. 17. The bank said earlier today that it raised $5 billion by selling 40.65 million shares at $123 apiece.

“People are questioning the sustainability of the first- quarter results,” said Roger Freeman, an analyst at Barclays Capital in New York who rates Goldman Sachs stock “neutral.” At the current share price, “you’re basically paying for an earnings recovery that is not guaranteed yet.”

To contact the reporter on this story: Christine Harper in New York at charper@bloomberg.net; Michael J. Moore in New York at mmoore55@bloomberg.net.

Last Updated: April 14, 2009 15:05 EDT