Investors continue to hold high levels of cash relative to the value of the market. The below charts graphs cash as a percent of the Wilshire 5000 ($DWC). A part of the increased percentage level of cash can be attributable to the decline in the market's value.
Source: Charles Schwab & Co.
Interestingly, the increased cash levels are being controlled within institutional money market funds.
Going back to January 2008 the Investment Company Institute reports total cash in money market funds has increased 17.39%. Individual money market fund assets over this same time period are essentially unchanged while institutional money market fund assets are up 28.46%