What are considered low-cost alternatives to equity index mutual funds?

The correct answer identifies stock index futures and equity swaps as low-cost alternatives to equity index mutual funds because these financial instruments typically offer greater flexibility and potentially lower transaction costs compared to traditional mutual funds.

Stock index futures allow investors to gain exposure to a stock index without needing to purchase the underlying stocks. This can lower overall expenses related to administrative costs, management fees, and trading costs, as they often have lower fees associated with them compared to mutual funds. Additionally, equity swaps can provide investors with similar positional benefits without the costs tied to ownership and management of mutual funds.

Other options, while relevant to investing, generally have different structures and cost implications. Real estate investment trusts, exchange-traded funds, and open-end mutual funds either carry their own specific fees, higher management costs, or lack the flexibility and cost efficiency associated with futures and swaps in the context of achieving low-cost index exposure.