June 9 (Reuters) - Activist investor Elliott Investment

Management has built a nearly $2 billion stake in Southwest

Airlines ( LUV ) and plans to push for changes aimed at

reversing the airline's underperformance, the Wall Street

Journal reported on Sunday, citing people familiar with the

matter.

Elliott is one of Southwest's ( LUV ) largest investors and plans to

engage with the airline's management team, the report said.

Southwest ( LUV ) and Elliott did not immediately respond to

Reuters' requests for comment.

The Dallas-based airline said in April it expected higher

costs and slower-than-expected revenue growth as U.S. planemaker

Boeing ( BA ) will now be able to deliver it just 20 aircraft

this year.

Elliott, one of the world's most prominent investors, is

known for pushing for changes at companies to boost shareholder

returns.