The largest shareholder of Los Angeles oil and gas developer BreitBurn Energy Partners L.P. is selling off about half its stake in the company with a public offering of 7 million BreitBurn partnership units.

Quicksilver Resources Inc., a Fort Worth-based oil and gas developer, on Wednesday priced the units at $19.78, 4 percent lower than Tuesday’s closing price. Quicksilver currently controls about 26 percent of the company.

Quicksilver granted underwriters, Deutsche Bank Securities, BofA Merrill Lynch, Citi and Wells Fargo Securities, a 30-day option to buy up to 1.05 million additional units of its stake in BreitBurn to cover any over allotments. If all shares were sold, Quicksilver’s stake would be reduced by 51 percent, but it still would remain the largest shareholder. The offering is expected to close by June 20.

The offering follows a legal dispute between Breitburn and Quicksilver, which had sued in 2009 for a larger role in the company. In February 2010, BreitBurn settled the litigation by paying Quicksilver $13 million and agreeing to management and board changes, including giving Quicksilver two seats on a reconstituted four-person board

Quicksilver said it plans to use the proceeds to pay down its own debt and for its own general corporate purposes.

Breitburn shares were down $1.17, or 5.7 percent, to $19.43 in midday trading on the Nasdaq.