Mutual fund flows are simply the net cash inflows and outflows in the mutual fund industry. Performance isn’t taken into account – only the net figure taken on a monthly or quarterly basis. Large outflows are generally a sign of pessimism by investors, while inflows are taken as a sign of optimism.

A look at the most recent Investment Company Institute (ICI) figure for estimated long-term mutual fund flows reveals large outflows during the past five weeks. For the week ending December 9, total outflows from mutual funds hit $11.16 billion. Equity funds showed the biggest drop off, losing $8.87 billion, and both hybrid funds and bonds lost more than $1 billion each as well.

It seems like an obvious assumption that this information tells us that investor sentiment is negative overall right now, but there’s something else to keep in mind.

Since about 2007, there’s been a consistent trend of fund flows leaving mutual funds and pouring into ETFs instead. Over the past eight years, more than $680 billion has leaked out of mutual funds, while ETFs have seen inflows of $646 billion. It’s a strong correlation that basically means for every dollar that’s left the mutual fund industry, a dollar has been invested into ETFs instead.

With that in mind, we can take a look at ETF fund flows to gain a clearer picture of investor sentiment. Unlike mutual funds, ETF flows are recorded on a monthly basis, so the most recent ICI data is taken from October. As expected, ETFs showed positive inflows.

Perhaps the most telling piece of data comes from money market funds. In October, total inflows hit nearly $44 billion compared to a net outflow of about $6 billion in September. It’s a large difference and a telling indicator that investors are looking for safer, more conservative, assets to protect their investments.

Interestingly, there was a large difference between institutional trading and individual trading as well. October’s numbers revealed that institutional funds had a net inflow of more than $51 billion, while funds targeted to individual investors showed outflows of almost $8 billion.

The trend of money moving from mutual funds into ETFs can’t be ignored as it presents another complication. Because of the perceived “sexiness” of ETF products, and the marketing towards investors who want to take matters into their own hands instead of leaving it up to Wall Street professionals, ETFs are getting a boost to inflows. The trend may come to an end, though, if the global economy slips into a recession and ETFs begin to fall faster than mutual funds.

Ironically, a recession could mean more investments for the mutual fund industry by investors who seek professional management after overseeing a collapse of their ETF values. Another contrarian viewpoint says that fund flows into money market accounts are actually a positive sign for stocks and that markets could be undervalued as well. This could explain the difference between institutional inflows and individual outflows for October. As we close out 2015, investors should take a look at how the year fared as a whole for fund flows to gain a macroscopic view of what 2016 might hold.