Why Sonos Rallied Nearly 15% Today

Shares of consumer electronic outfit Sonos (NASDAQ: SONO) were up 14.8% as of 3:40 p.m. ET Monday, according to data from S&P Global Market Intelligence, mostly in response to news that Standard & Poor's is adding the stock to its S&P 600 Small Cap Index.

S&P Dow Jones Indices -- the arm of S&P Global (NYSE: SPGI) that maintains several well-known market indices like the S&P 500 (SNPINDEX: ^GSPC) -- issued the announcement after Friday's close, notifying investors and fund managers that the S&P 600's makeup would be undergoing a slight change. As of this coming Wednesday, Chart Industries (NYSE: GTLS) will be moved from the S&P 600 Small Cap Index to the S&P 400 Mid Cap Index, replaced by Sonos.

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Source Fool.com