Two investment groups that lost on structured finance vehicles backed by subprime mortgages are pushing back after losing an attempt to hold the ratings agencies tied to the deals accountable in court.

Thomson Reuters says the investors – Commerzbank AG and Pennsylvania Public School Employees’ Retirement System – filed a notice of appeal in the U.S. Second Circuit Court of Appeals last week.

The investors previously saw their claims on a Morgan Stanley deal thrown out of court.

The original lawsuit alleged the ratings giants allowed certain mortgage-backed deals to receive high ratings even though they were supported by poorly underwritten mortgages, Thomson Reuters asserts.