New investors in the proposed merger of US Airways and America West Airlines will have a larger collective stake in the new company as the result of last Friday's $150 million commitment from Boston-based Wellington Management.

Wellington and four other investors would end up with a 49 percent share, according to new documents filed yesterday with the Securities and Exchange Commission, up from 41 percent originally due the first four -- Air Canada, PAR Capital Management, Peninsula Investment Partners and Air Wisconsin Airlines.

All told, the five investors are providing $500 million in new equity.

Because of the shift in ownership, America West shareholders will own a smaller stake, 39 percent instead of the 45 percent announced a few weeks ago. The same will be true of US Airways creditors -- 12 percent instead of 14 percent.

The merger, announced May 19, still faces a slew of regulatory and bankruptcy court approvals. Also, rivals have a month to put forth competing bids for US Airways and its assets. BusinessWeek reported yesterday that Alaska Airlines might bid for America West, citing sources "close to the industry." The BusinessWeek report claimed that Alaska Airlines did not want to disrupt the proposed America West-US Airways merger; instead, it might want to position Alaska Airlines as a large shareholder in the new airline.

BusinessWeek quoted an Alaska Airlines shareholder as saying, "Top management is considering a move to buy America West to gain critical mass and to better compete in the fiercely competitive industry -- and avoid being a takeover target itself."

America West declined comment about the BusinessWeek report.

An Alaska Airlines spokesman could not be reached for comment.