Omaha (Neb.) Public Power District hired Wellington to manage $25 million in active domestic midcap core equities, pending contract negotiations, said John Thurber, manager-finance and capital management. Wellington replaced Morgan Stanley, which ran the money in the same style and was terminated at the beginning of the year because of performance and personnel changes, Mr. Thurber said. The $470 million pension plan had parked the money in an S&P 500 index fund run by State Street Global Advisors. Capital Resource Advisors assisted. Bret Gallaway, vice president of corporate communications at Morgan Stanley, declined to comment.