A court battle is brewing between two Greek shipowners and shareholder litigants over a last-minute change in tactics that came just when it seemed a pair of securities-fraud lawsuits might be reaching a quiet end.

Shareholders suing George Economou’s DryShips and the Palios family’s Diana Containerships — now known as Performance Shipping — in two US federal court actions have asked a judge for permission to amend their complaints at the 11th hour.