UPDATE 5-New arrest in SocGen trading scandal

(Adds closing share price, further background)

By Sudip Kar-Gupta and Yann Le Guernigou

PARIS, March 12 (Reuters) - Police arrested another employee of French bank Societe Generale (SOGN.PA: Quote, Profile, Research) on Wednesday as they probe the world's biggest rogue trading scandal, Paris prosecutors said.

The arrest came as a U.S.-based law firm said it had filed a class action suit against SocGen, alleging France's second-biggest listed bank misled investors about its exposure in the subprime mortgage markets and failed to act on information about trades by Jerome Kerviel.

In January, SocGen unveiled 4.9 billion euros ($7.53 billion) of losses which it blamed on rogue deals carried out by Kerviel, a 31-year old junior trader at the bank.

The trading losses and writedowns related to the credit market turmoil have made SocGen, whose market capitalisation stands at over 30 billion euros, a possible bid target.

The latest person arrested in the trading scandal was working for a subsidiary of SocGen, the Paris prosecutor's office said.

A source close to the matter said the person being held works for SG Securities, the bank's share brokerage arm.

SocGen declined to identify the person or the division.