The Russell 2000 index of smaller companies dropped 15.38, or nearly 2 percent, to 760.06.
The Russell 2,000 index of small stocks rose 2.4 percent last week.
That is the biggest 12-month spread in the nearly 20 years the Russell index has been around.
The Russell 2000 index rose 1.67 points to close at 367.72.
The Russell 2000 index of smaller company issues closed down 1.4 percent.
And the Russell 2,000 index of smaller companies rose 7.22 points, to 325.62.
The Russell 2000 index of smaller companies is up 1.61 percent.
The Russell index of 2,000 smaller companies fell 0.12 point, to 463.66.
And the Russell 2000 index of small companies dipped half a point, to 460.77.
The Russell 2000 index closed the week down 0.54 percent.