The Financial Conditions Credit Spread Index (FXI) is an extension of AXI that incorporates data based on transactions of both financial and non-financial corporate debt instruments. An advantage of including non-financial issues is the much larger volume of transactions that can be exploited for robustness. It has been estimated that this scales up the dollar volume of covered transactions over the period 2014–2019 by factor of nearly 500%. AXI and FXI are highly correlated, especially over the past few years.   Image Source: NY Federal Reserve – Forum on Ongoing Innovation in Reference Rates for Commercial Lending