Market Vectors plans on swapping out the indices of its coal and gaming exchange traded funds in favor of in-house indices.

According to a press release, on or about Sept. 21, the Market Vectors Coal ETF (NYSEArca: KOL), which currently tries to reflect the performance of the Stowe Coal Index, will follow the new Market Vectors Global Coal Index.

KOL has dropped 27.5% year-to-date on the oversupply of coal in both the Atlantic and Pacific markets.

Additionally, the Market Vectors Gaming ETF (NYSEArca: BJK), which tries to reflect the performance of the S-Network Global Gaming Index, will begin tracking the Market Vectors Global Gaming Index.

BJK is down 13.8% over the past three months but up 2.8% year-to-date.