Eaton Vance Tax-Managed Buy-Write Opp is a United States-based diversified, closed-end management investment company. Its primary investment objective is to provide current income and gains. The secondary objective of the fund is capital appreciation. The fund invests in a diversified portfolio of common stocks and writes call options on one or more U.S. indices on a substantial portion of the value of its common stock portfolio to generate current earnings from the option premium. Its portfolio of investments consists of capital markets, chemicals, banks, biotechnology, media, and other sectors.