Driving the rally has been a diet of economic growth, moderating inflation, and Federal Reserve rate cuts, which act like rocket fuel for a group of companies that lean toward economically sensitive sectors like financials and consumer discretionary, and tend to have more floating rate debt. Together, they would give the market confidence that the S&P 600 can grow its sales, earnings, and margins—and push it up the 3% or so it needs to reach a new high.