California-based TrimTabs Investment Research has made its investment product that uses ETF flows as a contrary indicator to time the US stock market available for retail investors.

The quantitative investment product, called TrimTabs Flow Index, has previously only been available for institutional investors. The idea behind using ETF flows to time the US stock market "is based on the fact that retail investors are notoriously bad at market timing," the firm said.

“We’ve observed that investors in ETFs as a whole are horrible market timers, buying high and selling low,” said Leon Mirochnik, vice president of TrimTabs. “The TrimTabs Flow Index gives investors the opportunity to profit from these mistakes.”

The latest two-week market call based on the index advises investors to allocate half of their portfolio to US stocks and the other half to cash.

“Inflows into long US equity ETFs picked up sharply in recent weeks, which is a bad sign from a contrarian perspective,” Mirochnik said. “If inflows persist, the index will advise investors to pare their stock holdings even further.”