Aid is being sought for an ailing Santa Ana bank.

Directors of Capistrano Bancorp said they have entered negotiations to sell 80% of Capistrano National Bank to an unidentified group of investors for $4 million. The money is needed to satisfy regulatory demands for new capital to offset loan losses. The investors, believed to be Los Angeles businessmen, would buy 3.9 million new shares of bank stock for $3.5 million, or 90 cents a share, and 259,840 shares of the holding company’s stock for $500,000, or $1.92 a share.