Investor behavior can be highly unpredictable, but it's getting consistent in at least one regard.

More and more they're turning from managed funds and using indexes to express their sentiment about where the financial markets are heading.

Exchange-traded funds have started 2013 with a bang after taking in a record amount of new money the previous year.

Total assets under management have zoomed to $1.43 trillion, with a stunning 5 percent growth in just the first month or so alone.

While ETFs remain well behind the $9 trillion or so that the competing mutual fund industry still holds, the gap is clearly narrowing.

"That U.S. listed exchange traded funds (closed) out 2012 with such strong asset gathering - at or near a very considerable record - does engender a whole range of questions over the future of capital markets and especially equities," Nicholas Colas, chief market strategist at CovergEx, said in an industry analysis. "The data is clear: ETFs aren't just here to stay; they are here to conquer."

Based on the new money that's come in over the past year or so, the industry could double every four or five years. At that rate, it could overtake mutual funds in about 12 years.

David Fuller's view Investment managers who consistently outperform will always attract an enthusiastic following. However, they are very much in the minority, particularly during a valuation contraction cycle, such as we have seen since the year 2000.

Without a bandwagon bull trend, most investment managers have not only been unable to beat the market, partly due to the fees charged, but they have also struggled to produce gains on an annual basis.

Consequently, investors and portfolio managers are understandably looking much more closely at management fees. That has increased interest in ETFs, which are also easier to trade.