Which of the following functions is primarily used for historical spread analysis?

The function primarily used for historical spread analysis is HSA, which stands for Historical Spread Analysis. This tool is designed to help users analyze the historical performance of the spread between two or more securities over time, providing insights into how those spreads have fluctuated and allowing for better investment decisions based on historical data.

Unlike other functions such as RVD (Relative Value Desk), which focuses on relative value assessments, or RVM (Relative Value Monitor), which aids in real-time monitoring, HSA specifically targets the historical perspectives of spreads. YCRV (Yield Curve Relative Value) is more centered on yield curve analysis rather than spread performance over time. Thus, HSA stands out as the dedicated option for examining historical spreads, making it the correct choice for this question.