JMST is an ultra-short-term municipal bond ETF that has a fee subsidy in place to provide a teaser boost to the yield.
JMST holds super low duration bonds to minimize interest rate risk.
JMST takes greater credit quality risk than SUB, the main short-term muni ETF, with the hope the shortness will mitigate qualitative risks.
JMST is highly competitive with the fee subsidization.