Meme stock mania has been mighty kind to the small-cap Russell 2000 Index after its reconstitution last June. 

The total market capitalization of the Russell 2000 Index surged 84% from last year’s reconstitution (or the addition and subtraction of new companies to the index) to $3.5 trillion, FTSE Russell said in weekend tweet. This year alone, the Russell 2000 is up more than 16% compared to a 12% gain for the S&P 500.

"In 2020, overall capitalization for the U.S. equity market stayed fairly flat, decreasing by 1%. However, we’ve seen a surge in growth in the first half of 2021 with the total market cap in the Russell 1000 reaching $44.1 trillion. We have also seen a resurgence in market capitalizations of small cap companies in the Russell 2000 reflecting the overall bounce back of U.S. equity markets following the COVID-19 recession in early 2020," said FTSE Russell CEO Arne Staal.

To be sure, the index has been powered by massive gains in popular stocks among a new army of retail trades such as AMC (AMC) and GameStop (GME). 

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AMC shares have gained more than 700% in one-year's time, giving the money-losing movie theater chain a whopping $25 billion market cap. As for struggling GameStop, its stock has exploded 4,900% over the past year — it now sports a lofty $17.6 billion market cap.

Given each company's bulging market caps, they are likely to be removed from the Russell 1000. The index typically showcases companies with sub $5 billion market caps. 

Currently, the smallest company in the Russell 2000 Index is Velocity Financial (VEL). It boasts a market cap of $257.1 million, an increase of 171.2% from $94.8 million in 2020. 

FTSE Russell's changes to its various indexes will take place after U.S. stock markets close on June 25. The company points out the reconstitution will impact more than $10.6 trillion in investor assets benchmarked to, or invested in, products based on the Russell U.S. indexes. 

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Brian Sozzi is an editor-at-large and anchor at Yahoo Finance. Follow Sozzi on Twitter @BrianSozzi and on LinkedIn.

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