Cash Rich | ETF Trends### There's plenty of money on the sidelines that could move into stocks---Content continues below advertisement---Investors keep on building their cash war chest.Assets in money market funds currently stand at $7.7 trillion—which equals roughly one-tenth of the size of the entire U.S. stock market—down just slightly from their all-time high of $7.8 trillion in early January (see the chart). Last year, money market fund assets swelled by $860 billion—even as the Fed cut a key short-ter ...