The story

S&P Dow Jones Indices announced that Bloom Energy Corp., Illumina Inc., and Everpure Inc. will join the S&P 500 before the start of trading on September 21 as part of the quarterly rebalance. The three companies will replace Molson Coors Beverage Co., The Trade Desk Inc., and Builders FirstSource Inc. The changes ensure that each index is more representative of its market capitalization range.

Bloom Energy rose 5.63% in premarket trading after the announcement, while Illumina rose 1.04% and Everpure rose 2.70%. The Trade Desk, Molson Coors, and Builders FirstSource will all move to the SmallCap 600. The change will require ETFs, mutual funds, and other funds that track the S&P 500 to add shares of the three companies, potentially creating a wave of institutional buying ahead of the effective date.