The post-election outperformance of the firms "cyclicals versus defensive" basket of stocks has ceased; it now trails the S&P 500s advance since Nov. 8.
Concern stems from a surge in money chasing strategies that slice and dice the market based on various stock traits, factors like cheapness or volatility.
Nomura Holdings and Credit Suisse are among the most-active firms earning high fees by providing loans to help hedge funds buy capital-relief bonds.
Activists could gain more clout as stock ownership is concentrated among fewer owners, with funds shifting to indexed strategies, the firm suggests.
Big investors are motivated by signs the world has finally escaped from the decade of limp economic growth.