Small-cap stocks were largely buoyant Tuesday, and one of the biggest winners was Cambridge Display Technology ( OLED - Get Report).

Shares of the Britain-based company soared some 88% after Japan's Sumitomo agreed to buy it for a gigantic premium of $12 a share, or $285 million, in an all-cash deal that will likely close during the third or fourth quarter. Cambridge Display shares traded up $5.43 to $11.58.

Midwest Airlines ( MEH) also gained on M&A news. The Wisconsin-based company, which has been pursued by Airtran ( AAI) since late 2006 in the face of repeated rejection, now says it will begin discussions with the discount airline. AirTran's current bid is for around $15 a share in cash and stock.

Midwest also says it has recently attracted interest from "other strategic and financial parties" that it intends to explore. Its shares rose 12.9% to $14.23 in support of the Russell 2000, which lately climbed 4.69 points, or 0.6%, to 788.92.

The S&P SmallCap 600 similarly gained 0.7% as member Headwaters ( HW) blew away fiscal third-quarter expectations. The Utah-based company, which sells products and services to the energy and construction-materials markets, said earnings leapt by 40 cents a share from last year to 98 cents -- double the amount analysts were seeking. Revenue, at $336.3 million, was also well above the consensus. Shares surged 13.4% to $16.99.

Faro Technologies ( FARO - Get Report) ramped up second-quarter earnings more than sixfold year over year to 39 cents a share, or $5.8 million, and women's-apparel retailer Cache ( CACH) reported a 6% climb in July same-store sales. The New York-based company also said it will buy back up to a million of its shares.

Florida-based Faro, which makes computerized measurement devices, soared nearly 24% to $37.33. Cache bounced 12.4% at $17.28.

On the flip side, industrial-equipment distributor DXP Enterprises ( DXPE - Get Report) plummeted 25.5% on a wide earnings miss for the second quarter. The Houston-based company made 56 cents a share, or a nickel more than it did last year, but two analysts had called for 67 cents. Shares were changing hands at $33.

LCA-Vision ( LCAV) also fell far short for the second quarter with income of just $7.4 million, or 36 cents a share, on revenue of $69.7 million. The Street was looking for 44 cents a share on sales of $74 million. The Cincinnati-based company also shaved its full-year outlook down to a profit of $1.90 to $2 a share vs. prior guidance of $2.05 to $2.15 a share. Analysts are seeking $2.11 a share.

Shares of LCA-Vision, which operates laser-eye-surgery centers, fell $7.24, or 16.8%, to $35.75 in recent trading.