A plunge in Star Bulk Carriers' shares can be traced back to a deal the Petros Pappas-led shipowner made with Songa Bulk back in July, according to a prominent analyst.

Jefferies' Randy Giveans rejected claims that the drop was a result of the announcement of a share incentive plan for company executives.

Instead, he said the share fall was related to a six-month trading restriction placed on stock connected to Star Bulk's acquisition of 15 Songa Bulk vessels.