MSML
iShares MSCI USA Small-Cap ETF
stockNYSEETF

For you as a holder, not much really changes. ILCB is now MLRG and ISCB is now MSML (switched on 5 Oct). The large/mid fund now tracks the MSCI USA index, which is about 527 stocks covering roughly 85% of the US market. So you lose the long tail of smaller names and the fund ends up a bit more concentrated in the big companies, but those dropped stocks were tiny weights anyway. The fee's still 0.03%. I'd just keep an eye on tracking difference over the next year or so. If it stays tight to the new index and the fee doesn't change, there's nothing you need to do.