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"Buy an S&P 500 ETF" is maybe the most ubiquitous advice in the modern investing world. Financial advisers tell you to do it. I tell you to do it . And we even provide descriptions of the best index funds to buy .

For the most part, investors listen. Dozens of ETFs are tethered to the S&P 500 in various ways, but only four directly track the index. And they’re among the most popular funds on the planet:

The iShares Core S&P 500 ETF ( IVV ) has assets under management of $821.8 billion. The Vanguard S&P 500 ETF ( VOO ) has $817.5 billion, the State Street SPDR S&P 500 ETF Trust ( SPY ) $751.5 billion. And the State Street SPDR Portfolio S&P 500 ETF ( SPYM ) has $140.8 billion.

From just $107.88 $24.99 for Kiplinger Personal Finance

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