A quiet offseason for the Mariners and Yankees is about to get a lot louder as the teams are in the process of finalizing a four-player trade that would swap two of the Major Leagues' top young prospects -- power-hitting catcher Jesus Montero to Seattle in exchange for rookie All-Star pitcher Michael Pineda, according to a source with knowledge of the deal.

Though the teams have not officially announced the trade, Seattle would send Pineda and Minor League pitcher Jose Campos to the Yankees for Montero and 24-year-old right-hander Hector Noesi.

It is the Mariners' policy not to confirm or comment on deals until physicals are taken, which could take time in this case since Pineda was in the Dominican Republic and Montero at his home in Venezuela when word of the deal broke Friday.