The Standard & Poor's 500 index fell into correction territory Friday — dropping more than 10% since hitting its all-time high — and closed the week at 2,658.69.

The total return on the S&P 500 in the third quarter of 2018 was a strong 7.7%, but volatility since lopped off 9% of its value from its all-time closing high.

Share prices had hit a closing peak on September 20 of 2930.75 before tumbling to a 2629.18 low on Friday morning, meeting the definition of a market correction. Market corrections of 10% or even 15% on swings in investor sentiment are not uncommon events in long-term bull market periods historically accompanying economic expansions. Bear market drops of 20% are much less common and most bear markets coincide with economic recessions. No evidence of a recession was on the horizon Friday.