Bloom Energy's S&P 500 addition triggered mechanical buying pressure, but rival fuel cell stocks with no connection to the rebalance are surging alongside it, pointing to a second, more powerful force at work in the sector.

FuelCell Energy is rising Friday, attempting a modest rebound as investors weigh long-term AI power demand against near-term margin pressure.

Bloom Energy's S&P 500 addition triggered mechanical buying pressure, but rival fuel cell stocks with no connection to the rebalance are surging alongside it, pointing to a…