It will operate as part of Copal Partners a unit of Moody's Analytics.
"Amba is highly regarded for its offerings to investment research firms and asset managers, and Copal is known for its strong services for corporate finance," Mark Almeida, President of Moody's Analytics said.
"Together, their scale, talent and resources offer global financial institutions a broader array of research and analytics."
Founded in 2003, Amba provides outsourced investment research and analytics to asset managers, investment banks, broker-dealers, insurance and alternative investment firms.
Amba is expected to bring revenues of 39 million US dollars in 2013.