The NZX 50 index (Ticker:^NZ50) is designed to measure the performance of the 50 largest stocks listed on the Main Board of the New Zealand Exchange by free float-adjusted market capitalization. The index covers approximately 90% of New Zealands equity market capitalization. The index was introduced as the NZSX 50 Index in March 2003. In 2015, the index was renamed to S&P/NZX 50 Index reflecting a partnership between NZX and S&P Dow Jones Indices. As part of the partnership, S&P DJI has assumed responsibility for calculating, publishing, and distributing all NZX indices.