CORRECTION: As others have pointed out, many ETFs secure the investment with a custodian. This makes these ETFs immune to a sole bankrupcy of the issuer. In cas

CORRECTION: As others have pointed out, many ETFs secure the investment with a custodian. This makes these ETFs immune to a sole bankrupcy of the issuer. In case of a domino effect or a close interwovenness between issuer and custodian this might turn out problematic nevertheless. But there are many kinds of ETFs, most notably swap-ETFs, that are not backed by real stocks. For these, what I have written applies without restriction.