ABB LTD Sponsored ADR – US0003752047 – 2748472
With a depository receipt (such as an ADR), the trading/listing of the ADR is irrelevant for ISA qualifying purposes. The key point is whether the underlying shares represented by the ADR are ISA qualifying in their own right ie. are they listed on a recognised stock exchange or admitted to trading on a recognised stock exchange in the EEA or UK.
The shares in ABB Ltd (ISIN – CH0012221716 – link below) are listed on the SIX exchange in Switzerland, which is a recognised stock exchange, so assuming that these are the shares represented by the ADR, the ADR will be ISA qualifying.