Citigroup said it has a cautious view on the U.S. small-and mid-cap companies on concerns over earnings pressure in the second half amid the euro zone crisis and the political uncertainty in the United States.

Analyst Scott Chronert downgraded the small and mid-cap technology sector to "market weight", saying expectations for margin improvement for the group may be tough to meet even as valuations remain attractive.

Chronert upgraded the health care and utilities sectors to "overweight" on valuation.

The consumer staples sector was upgraded to "market weight" from "underweight" by the analyst, who noted that positive earnings estimate revisions have been on the rise for these companies.

He maintained his "market weight" rating on consumer discretionary, industrials, materials, and telecom sectors, and an "underweight" on financials.

The analyst added business process outsourcing provider Convergys Corp, biopharmaceutical company Amarin Corp and Great Plains Energy Co to his focus list, while removing ExlService Holdings Inc.

The S&P MidCap 400 index closed at 925.63 points, while the Russell 2000 closed at 764.64 points on Monday.