ICE BofA US Corporate Index Option-Adjusted Spread

Starting in April 2026, this series will only include 3 years of observations. For more data, go to the source. The ICE BofA Option-Adjusted Spreads (OASs) are the calculated spreads between a computed OAS index of all bonds in a given rating category and a spot Treasury curve. An OAS index is constructed using each constituent bond's OAS, weighted by market capitalization. The Corporate Master OAS uses an index of bonds that are considered investment grade (those rated BBB or better). When the last calendar day of the month takes place on the weekend, weekend observations will occur as a result of month ending accrued interest adjustments. This data represents the ICE BofA US Corporate Index value, which tracks the performance of US dollar denominated investment grade rated corporate debt publicly issued in the US domestic market. To qualify for inclusion in the index, securities must have an investment grade rating (based on an average of Moody's, S&P, and Fitch) and an investment