Activist hedge fund Elliott Investment Management has won enough support from Phillips 66 shareholders to secure two board seats on the U.S. oil refiner's board of directors in one of the country's biggest corporate fights this year, two people familiar with the preliminary vote said on May 21.

Elliott is pressing Phillips 66 to sell some assets to become a pure-play refiner, improve performance at its refining business and improve corporate governance. It sought to add four newcomers to the board this year.

Preliminary voting data show that Phillips 66 managed to partially fend off Elliott's push, however, with each side winning two of the four seats that were up for election.

The results also show that Elliott received no support from any of the large index funds that often control such corporate votes, according to two sources. But it did receive 40% support from Phillips' employee pension fund, one of the sources said.

This is the first time ever that Elliott, one of the world's busiest activist investors, has seen one of its campaigns go to a vote.