Sealink Funding Ltd., an Ireland-based entity created to manage residential mortgage-backed securities, is suing the Royal Bank of Scotland (RBS) over RMBS investments that soured, making it the third financial institution in the firm's sights over the past four months. 

Sealink alleges in a lawsuit filed in a New York state court that it acquired $90 million in RMBS securities from Royal Bank of Scotland based on alleged misrepresentations about the underwriting standards used to measure the quality of the mortgages pooled into securities sold to Sealink. 

This is the third lawsuit Sealink has filed against a major bank that put together RMBS securities prior to the subprime fallout.

The firm filed multibillion-dollar lawsuits against Bank of America (BAC) and JPMorgan Chase (JPM). Sealink claims the firms sold RMBS backed by poorly underwritten mortgages.

The suit against JPMorgan was over $2.4 billion of RMBS purchased from 2005 through 2007, while the BofA case was over $1.6 billion of RMBS acquired in 30 offerings between 2005 and 2007 from Countrywide.