An interest rate call option (also known as a yield call option) is a type of financial derivative contract that grants its holder the right, but not the obligation, to receive a variable rate while paying a fixed rate of interest over a pre-determined period of time. It is an agreement between two parties, known as the holder and the issuer, that specifies the payments and returns for each participant. Interest rate call options are considered one of the riskiest and most sophisticated types of derivatives, but they provide investors with a less expensive and more efficient way of hedging their investments from the volatility of interest rates.

Interest rate call options are generally used by lenders and borrowing institutions. These organizations seek to protect themselves from rising interest rates by locking in a fixed rate for a predetermined period. Interest rate calls also function as a means for investors to hedge their investments when faced with the threat of floating interest rates. With an interest rate call option, investors can lock in a predetermined maximum interest rate, shielding themselves against unexpected rate hikes.

Interest rate call options can be put in contrast to interest rate puts, which grant the holder the right, but not the obligation, to receive a variable rate while paying a fixed rate of interest. Puts are much less risky and enable greater buffer against the volatility of interest rates.

In order to adequately use interest rate call options, investors must have an accurate understanding of the risks involved in this type of derivative. The potential reward is a locked interest rate that can protect against the uncertainty of the market. However, this reward comes with the risk that the holder may have to pay more than the fixed interest rate if the interest rate during that period rises above the predetermined cap. In addition, the holder must be aware of the issuer's credit risk, as the issuer may default if their financial position erodes before the end of the option period.

Overall, understanding the risks and rewards associated with interest rate call options is essential for investors before entering a contract. This derivative instrument is an effective way for lenders and investors to protect their investments from rising interest rates, but it can potentially backfire if the terms of the contract are not satisfactory.