Bank of America analysts have noted a significant increase in bullish sentiment towards the S&P 500, as reflected by their top contrarian sentiment indicator, the Sell Side Indicator (SSI). The indicator is described as 'getting bullisher and bullisher,' with strategists' allocation to stocks reaching a 2.5-year high. Additionally, the BofA Bull & Bear Indicator rose to 6.2 last week from 6.1, marking its first weekly rise in the past month due to substantial inflows into stocks and bonds. Jim Paulsen highlighted that the recent pop in the SPEW index might signal a new leg higher for the stock market, potentially with broader participation.