The S&P 500 rose 0.8 percent last week. While it was flat for March, it rose 5.5 percent for the first quarter as a whole.
The sustained rally in the US stock market has made stocks expensive, but Michael Batnick at Yahoo Finance pointed to a Credit Suisse paper that noted that US companies have become more profitable in recent decades, which might justify their higher valuations.
However, John Hussman wrote that going forward, US economic growth is likely to be constrained by slowing labour force and productivity growth. Slowing economic growth and a tighter laboor market will in turn widen the wage share of GDP and narrow corporate profit margins.