(Adds statement from Moody's)
MEXICO CITY, Oct 16 (Reuters) - The credit ratings of seven large banks could be at risk if a probe by Mexico's antitrust watchdog found them guilty of market manipulation and collusion in the government bond market, ratings agency Moody's said on Wednesday.
That watchdog, Mexico's Federal Commission for Economic Competition (Cofece), said earlier this week that it had concluded an investigation into the alleged bond market transgressions. Any banks implicated would face sanctions and fines if found guilty, it said.
Cofece did not name the banks. But Moody's identified them as Banco JP Morgan in Mexico, Banco Santander Mexico, Bank of America Mexico, Barclays Bank Mexico, BBVA Bancomer, Citibanamex and Deutsche Bank Mexico.
With the exception of Deutsche Bank Mexico, all banks mentioned by Moody's are authorized by the government as market makers, according to a finance ministry document dated July 2019. HSBC Mexico is also authorized but was not named by Moody's.
Banamex, Barclays and JP Morgan declined to comment. Santander earlier this week said it would cooperate with authorities. The others did not immediately respond to a request for comment.
Cofece said its investigation was the largest into public debt sales and reflected the Mexican government's efforts to increase market oversight.
The investigation started almost 2-1/2 years ago and centers on trading activity between October 2016 and April 2017.
"Trading is an important source of earnings for Mexican banks," Moody's said. "Among the seven banks, investment banks such as Barclays, JP Morgan and Bank of America rely most heavily on trading income."
In late September, a U.S. judge dismissed a proposed class action against several large banks for allegedly rigging the market for Mexican government bonds, according to a court filing.
U.S. District Judge Paul Oetken in Manhattan said in his opinion the plaintiffs - eight pension funds who he said could amend their complaint - failed to allege a direct link between each defendant and a conspiracy. (Reporting by Delphine Schrank, Stefanie Eschenbacher and Abraham Gonzalez; editing by Frank Jack Daniel and Tom Brown)