NEW YORK, Oct. 16 -- Funds that mirror MSCI's global stock benchmarks could be forced to sell Strategy, the Bitcoin-buying software company led by Michael Saylor, by the end of November. MSCI said late Thursday that it will make "non-operating companies" ineligible for its Global Investable Market Indexes, a screen its own August trial run said Strategy would fail.

MSCI will implement the proposal "with minor modifications" in its November index review, effective as of the close of November 30, according to the announcement, which carries an October 15 date. An issuer that fails an initial test for "substantial operating assets" becomes ineligible if it is flagged on four or more of five financial ratios. Current constituents come out on...