Standard & Poor's may face securities fraud charges for ratings given to six commercial mortgage-backed securities issued in 2011, the credit rating company said.
The potential civil lawsuit is the latest legal issue for the credit rating company, which along with its competitors have faced intense regulatory scrutiny following the financial crisis.
S&P, a unit of McGraw Hill, disclosed on Wednesday that it had received a Wells notice from the Securities and Exchange Commission indicating its enforcement division staff intended to recommend that the five member commission authorize civil charges against the company.
Read More Higher mortgage rates not deterring buyers
"S&P has been co-operating with the commission in this matter and intends to continue to doso," it said in a statement. S&P said the Wells notice related to the six securities "and public disclosure made by S&P regarding those ratings thereafter".
A Wells notice is no guarantee that the SEC will bring charges. In 2011 the SEC sent a Wells notice to S&P over its ratings of a collateralize debt obligation called Delphinus. No charges were brought against S&P, however Mizuho Securities and three former employees were charged for misleading investors in the CDO. Mizuho paid $127 million and the former employees also settled without admitting or denying wrongdoing.
The new Wells notice relates to CMBS sold in 2011. S&P withdrew ratings on a $1.5 billion CMBS after discovering inconsistencies in how its rating methodology was applied. That withdrawal prompted an internal review, which highlighted methodology inconsistencies for six other CMBS it rated in 2011.
At the time the initial SEC investigation came to light in 2013, S&P told news organisations: "We reviewed the application of our CMBS methodology and determined that the approach used for new transactions rated in 2011 produced results that were consistent with Standard & Poor's rating definitions and resulted in no ratings changes.
S&P will have an opportunity to present its case to the SEC to try to convince them civil charges are not warranted.
Read MoreAs S&P nears 2000, traders say keep an eye on this
The ratings company faces a Department of Justice civil lawsuit filed in 2013 seeking more than $5 billion.
The DoJ has alleged S&P inflated rating on residential mortgage-backed securities in the years leading up to the financial crisis.
McGraw Hill, whose stock dropped 27 percent the week the DoJ lawsuit was announced, is fighting the allegations and the case is proceeding in court.