Goldman Sachs Inc may have to cough up a big fine to settle the civil lawsuit brought by U.S. regulators and the issue poses the biggest threat to the reputation of the influential bank, analysts said.

Since it is a civil complaint, it may not be life threatening for the company and the worst could be a large monetary fine, Citigroup analyst Keith Horowitz said.

Goldman Sachs was charged with fraud by the U.S. Securities and Exchange Commission (SEC) over its marketing of a debt product tied to subprime mortgages that was designed to fail.

Based on our understanding, this implies the government did not find sufficient evidence to justify a criminal action, although that cannot be ruled out in the future, Horowitz wrote in a research note.

Analysts believe that the outcome of the proposed financial reforms is still unclear and the suit will only add to the uncertainty.

Oppenheimer Equity Research downgraded the stock to perform from outperform saying the shares are likely to suffer in the near term although Goldman will continue to post strong earnings.

At the moment, it looks as if the SEC is pursuing an agenda aimed specifically at Goldman. That likely will keep a cloud over the stock for now, Oppenheimer analyst Chris Kotowski said.

Goldman shares sank $24.13, or 13 percent, to $160.14 in afternoon trade on the New York Stock Exchange, after earlier falling to $155.55.

(Reporting by Supantha Mukherjee and Anurag Kotoky in Bangalore; Editing by Gopakumar Warrier)