WAM is the weighted average maturity of the portfolio. The WAM calculation utilizes the interest-rate reset date, rather than a security's stated final maturity, for variable- and floating- rate securities. By looking to a portfolio's interest rate reset schedule in lieu of final maturity dates, the WAM measure effectively captures a fund's exposure to interest rate movements and the potential price impact resulting from interest rate movements.
WAL is the weighted average life of the portfolio. The WAL calculation utilizes a security's stated final maturity date or, when relevant, the date of the next demand feature when the fund may receive payment of principal and interest (such as a put feature). Accordingly, WAL reflects how a portfolio would react to deteriorating credit (widening spreads) or tightening liquidity conditions.