As a price index, the SMI is not adjusted for dividends, but a performance index that takes account of such distributions is available ( the SMIC-SMI Cum Dividend ).
2.
The first was the tax structure in the UK : for a time, capital gains were bond washing " or " gilt stripping " : selling the gilt or other bond cum dividend, and buying it back ex dividend, thus forfeiting the interest income in exchange for a tax-free capital gain.