Experts are split on whether stocks will beat the 'September Effect' – Ed Yardeni warns of pain while Bank of America sees room for gains

• September is historically considered the worst month of the year for stocks, in what is known as the "September Effect."  
• But this year, market experts appear divided over whether US equities will repeat the pattern or defy it. 
• Here's where 5 top voices see stocks heading in September and ahead. 

September has historically been a weak month for stocks, although there's no real explanation for the pattern beyond statistical seasonality. The phenomenon even has a nickname: "The September Effect."