A similar story to SKHY/SKHYNIX is TSM/2330 i.e. the TSM ADR, which was issued back in 97' at a 1:5 ratio against TSMC (ticker 2330 on the Taiwanese stock market). My understanding is that the arbitrage is difficult to perform when the ADR trades at a premium (as seen below). There is a limit on ADR issuance (converting Taiwan-listed shares into TSM), and therefore a limit to how easily the spread can be closed when TSM trades at a premium to TSMC. Not sure how similar this is to the current SKHY/SKHYNIX situation so keen to hear opinions/insights. If it is similar and there's a strict limit on ADR issuance it could potentially mean that the premium persists for longer? Chart slightly overstates premium at times due to differences in open hours on the American vs Taiwanese market.(Thor)