ALEXANDRIA, Va. (AP) – Boston-based investment adviser Wellington Management Co. will invest $150 million in the merger of US Airways Group and America West Holdings Corp., US Airways said in a court filing.

Wellington’s investment boosts to $500 million the amount of equity raised from five investors to help complete the merger and bring Arlington, Va.-based US Airways out of bankruptcy.

US Airways and America West announced plans to merge May 19 with a goal to create an airline to better compete with lower-cost rivals. The new airline would keep the US Airways name, and create the sixth largest airline in terms of passenger miles.

US Airways already had secured $125 million from Eastshore Holdings LLC, $100 million from Par Capital Management Inc., $75 million from Air Canada parent ACE Aviation Holdings Inc. and $50 million from Peninsula Investment Partners LP.

“The terms of the Wellington Investment Agreement … are substantially similar to the investment agreements between (US Airways) and each of ACE, Eastshore, Par and Peninsula,” US Airways wrote in the amended filing Friday with the U.S. Bankruptcy Court in Arlington.

But the deal with Wellington, which has about $470 billion in assets under management, differs in that Wellington will pay $16.50 for new common stock, compared to the $15 per share the others must pay. And unlike the others, Wellington will not designate a director on the merged airline’s board and will not be entitled to a breakup fee if it is displaced by another investor.

A judge is expected to establish a framework and times for approval of the proposed merger on Tuesday.