John Hancock Preferred Income Fund III is a closed-end, diversified management investment company. Its investment objective is to provide a high level of current income consistent with preservation of capital. The fund's secondary investment objective is to provide growth of capital to the extent consistent with its primary investment objective. It seeks to achieve the objectives by investing a majority of its assets in preferred stocks and other preferred securities, including convertible preferred securities. The portfolio composition of the company consists of the U.S. preferred securities, foreign preferred securities, common stocks, corporate bonds, and the short-term investments.