Idaho tops the list of states for performance of S&P 500 stocks based there during the past year, according to a USA Today analysis of data from S&P Capital IQ.

To be sure, the Gem State has only one company in the S&P 500 — Micron Technology, a manufacturer of semiconductors. But its shares soared 139 percent in the last year.

Among states with at least eight companies in the index, Connecticut takes first place. Its 16 S&P 500 companies averaged a 40.4 percent increase in their share prices during the last year.

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Harman International, a maker of audio products, led the way in the Nutmeg State, with its stock jumping 106 percent.

Maryland ranked second among states with at least eight S&P 500 companies. Its eight companies averaged a gain of 38.6 percent in the last year.

Following Maryland in the category are Pennsylvania, whose 18 companies averaged 29.5 percent; Virginia, whose 15 companies averaged 29.3 percent; and California, whose 64 companies averaged 27.4 percent.

As for the overall S&P 500, it has gained about 19 percent during the year through Monday morning. Both that index and the Dow Jones Industrial Average hit record highs Monday.

"There's a fair amount of skepticism over if we are at peak valuations," Michael Arone, chief investment strategist at State Street Global Advisors, tells Bloomberg.

"My view is the Goldilocks economy is back — not too cold, not too hot, but just right. We're starting to see companies do capital expenditures and M&A [mergers and acquisitions] to invest in their businesses."

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