While the exchange traded funds (ETFs) work to make their mark with investors and get a bigger slice of the mutual fund pie in terms of assets, fund managers don’t appear to have to be sold on them.

Last year, 17 out of 20 of the largest mutual fund companies were using them last year. Providers that are most popular among managers are Barclays Global Investors, State Street Global Advisors, Vanguard Group and Invesco PowerShares.

So, is this acceptance much more than an endorsement of the ETFs value for active managers? Some say it indicates how hard single-stock selection can be. One of the main ways that managers are using ETFs is for cash equalization or “parking” cash in ETFs for a short time period until the fund invests in single stocks, reports David Hoffman for Investment News.

It turns out to be proper for a fund manager to also use ETFs for a long-term sector rotation strategy, as long as the client is aware of this. Despite concerns or naysayers, it is evident that mutual funds will continue to use ETFs for their advantage.

According to a study by SSGA, the top ETFs among mutual funds by assets are:

• iShares Russell 2000 ETF (IWM) $1.8 billion
• iShares S&P 500 ETF (IVV) $1.4 billion
• SPDR S&P 500 (SPY) $1.3 billion

Tags: IVV, IWM, Large-Cap, Russell Indexes, S&P 500, Sector ETFs, Small-Cap, SPY