** Shares of fire and safety services provider APi Group APG.N up 6.1% premarket to $51.95, a fresh record high, as co set to join S&P MidCap 400 index .IDX next week

** APi to replace U.S. Steel in the IDX effective Tues, Jun 24, the S&P Dow Jones announced after the bell on Weds

** Nippon Steel 5401.T on Weds closed its ~$15 bln acquisition of U.S. Steel

** Stephens analyst Melissa Roberts said she expects passive funds will need to purchase 27 mln APG shares, which implies nearly 16 days of buying demand based on stock's 3-mth avg daily trading volume of 1.8 mln shares

** New Brighton, Minnesota-based co has ~276.8 mln shares outstanding for $13.6 bln market cap

** APG shares on Weds touched record intra-day high of $49.55 before finishing session at $48.95, up 36% YTD

** 9 of 10 analysts rate APG shares "strong buy" or "buy", 1 rates "hold" with median PT of $54, up from $48 a month ago, LSEG data reflects

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@thomsonreuters.commailto:lance.tupper@tr.com 1-646-279-6380))