Shares of

Dollar General

(DG) - Get Report

were among the

NYSE's

winners Monday, soaring 27% after the retailer agreed to be acquired by Kohlberg Kravis Roberts for about $6.9 billion.

The private equity firm will pay $22 a share, representing a 31% premium to Dollar General's closing price of $16.78 on Friday. Including the assumption of debt, the deal is worth about $7.3 billion. The transaction is expected to close during the third quarter.

Shares of Dollar General were trading up $4.48 to $21.26. The deal sent shares of competitor

Family Dollar Stores

(FDO)

up 10% to $31.43, while

Dollar Tree

(DLTR) - Get Report

was adding 80 cents, or 2.2%, to $36.46.

Sierra Health Systems

( SIE) surged 16% after the health care services company agreed to be acquired by

UnitedHealth Group

(UNH) - Get Report

for about $2.6 billion in cash. The deal is worth $43.50 a share, representing a 21% premium over Sierra Health's closing price of $35.90 on Friday. The acquisition is expected to close by the end of 2007 or sooner. Shares of Sierra Health were up $5.63 to $41.53.

Shares of

Spartech

(SEH)

rose 8% after the plastics maker posted better-than-expected first-quarter earnings. For the period ended Feb. 3, the company earned $8.1 million, or 25 cents a share, on revenue of $347.3 million. Analysts polled by Thomson First Call expected earnings of 20 cents a share and a top line of $349.8 million. A year earlier, the company earned $5.7 million, or 18 cents a share, on revenue of $343.6 million.

For 2007, Spartech now sees earnings of $1.55 to $1.62 a share. Previously, the company predicted earnings of $1.55 to $1.60 a share. Analysts project earnings of $1.57 a share. Shares were adding $2.07 to $28.38.

Shares of

Steel Dynamics

(STLD) - Get Report

rose modestly after the steel company boosted its first-quarter earnings forecast. The company now sees earnings of 94 cents to 98 cents a share, up from an earlier view of 85 cents to 90 cents a share. Analysts project earnings of 88 cents a share. The company said market conditions for flat-rolled steels have improved since mid-January. Shares were trading up 25 cents to $39.03.

Suntech Power Holdings

(STP)

fell 5% after the maker of solar-power cells posted mixed fourth-quarter results. The company reported adjusted earnings of $35.5 million, or 23 cents a share, on revenue of $217.9 million. The bottom line topped analysts' expectation of 20 cents a share, but the revenue was shy of Wall Street's projection of $221.4 million. In the year-earlier quarter, Suntech recorded adjusted earnings of $16.8 million, or 13 cents a share, on revenue of $89 million.

Looking ahead, Suntech forecast first-quarter revenue of $220 million to $228 million. Analysts project revenue of $232.9 million. Shares were down $1.99 to $37.31.

Shares of

Energy Partners

(EPL)

traded actively after the oil and gas concern said that a review of strategic alternatives resulted in no definitive offers for the company to be acquired. Instead of a sale, the company plans to buy back up to 8.7 million of its shares, or 22% of its outstanding stock, in a tender offer of $23 a share. Energy Partners may repurchase another $50 million of stock following the conclusion of the current offer, which is valued at $200 million. Shares were trading down 8 cents to $17.92 on more than triple their average daily volume.

NYSE volume leaders included

Motorola

( MOT), up 19 cents to $18.66;

CVS

(CVS) - Get Report

, down 51 cents to $32.09;

Ford

(F) - Get Report

, down 5 cents to $7.88;

Caremark

( CMX), down $1.16 to $60.74;

General Electric

(GE) - Get Report

, down 13 cents to $34.19;

Altria

(MO) - Get Report

, up 14 cents to $87;

Taiwan Semiconductor

(TSM) - Get Report

, up 24 cents to $10.99; and

EMC

(EMC)

, down 5 cents to $13.

Among

Nasdaq's

volume leaders were

Sun Microsystems

(SUNW) - Get Report

, up 6 cents to $6.33;

Intel

(INTC) - Get Report

, up 9 cents to $19.19;

Level 3 Communications

(LVLT)

, down 1 cent to $6.31;

Sirius Satellite Radio

(SIRI) - Get Report

, down 2 cents to $3.40;

Amgen

(AMGN) - Get Report

, down $1.57 to $59.29; and

Microsoft

(MSFT) - Get Report

, down 4 cents to $27.25.