MLN is one of the funds to focus exclusively on US AMT-free, long-dated municipal bonds, while still attempting to capture a full range of issuers and market sectors. Eligible securities must have a fixed coupon schedule and at least 17 years remaining to maturity. The fund weights constituents by market value and mainly includes investment grade bonds with high overall credit quality. The fund uses a sampling method in tracking the index, which means it will invest in a sample of securities that collectively have an investment profile similar to that of the underlying index. Rebalancing occurs monthly. Prior to March 1, 2022, the fund tracked the Bloomberg AMT-Free Long Continuous Municipal Index. Then until November 30, 2022, the fund used a transition index to gradually broaden its exposure before tracking its current index.