FIRM SELLS ENTIRE ALLEGHENY INT'L <AG> STAKE Southeastern Asset Management Inc and its two controlling shareholders said they sold their entire 5.6 pct stake in Allegheny International Inc. In a filing with the Securities and Exchange Commission, Southeastern, a Memphis, Tenn. investment advisor, said it sold the entire 604,000-share stake between March 13 and 16 at prices ranging from 24.25 to 24.625 dlrs each.