I find it irritating that the usual descriptions of the SPDR ACWI IMI state that it invests in approx. 9000 stocks. According to the factsheets from Street Global Advisors, however, it "only" invests in approx. 3600 shares, similar to the FTSE all world.
@Dominik_76 This is because they sample the shares in the index, i.e. they do not buy all 9000 shares but select a "representative number of shares" that tracks the index "sufficiently accurately". There is a bit of math behind this, but ultimately they try to keep the tracking error to the calculated index with the 9000 shares as low as possible.
