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 also gained on M&A news. The Wisconsin-based company, which has been pursued by Airtran 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.