KEY POINTS
  • The reversal in momentum, which seemed to abate this week, could be explained by a sudden stop in tax loss harvesting, some on Wall Street said.
  • Investors often sell losing stocks to lower their capital gains tax bill.
  • Tax loss selling might have stopped due to speculations the Trump administration would pass a bill to reduce capital-gain taxes, according to Barclay's head of equity derivatives strategy Maneesh Deshpande.
A trader works at the New York Stock Exchange in New York.

What exactly happened during the "once in a decade" stock market rotation earlier this month that rocked investors? It might've just been a one-off technical move and not based on fundamentals.

A huge rotation out of momentum into value names took place suddenly last week. Many read the phenomenon as a warning sign as stocks with superior growth have led the market's bull run in recent years and said a rebound in interest rates was the catalyst. However, the reversal in momentum, which seemed to abate this week, could be explained by a sudden stop in tax loss harvesting, some on Wall Street said.