Shares of Cytyc Corp.(NASDAQ: CYTC) rose more than 20 percent on Monday, a day after an announcement that Hologic, Inc. (NASDAQ: HOLX) agreed to buy the company for $6.2 billion.

Share of Cytyc rose $7.95, or 22.68 percent, to close at $43.00 on the Nasdaq Stock Market. Shares of Hologic, however, dropped $3.61, or 6.27 percent, to $54.00. Both firms specialize in medical treatments and procedures for women.

By combining our companies' complementary, best-in-class products and technologies, we expect to drive enhanced growth and value creation, said Jack Cumming, Hologic's Chairman and Chief Executive Officer.

The combined entity is also expected to generate approximately around $30 million in annual cost savings from enhanced efficiency of sales and marketing efforts, increased purchasing scale, sourcing and logistics efficiencies and shared administrative services.

Upon the deal's completion, expected in the close of the third quarter, Cytyc shareholders will hold 55 percent of the firm and Hologic will own 45 percent.

For Hologic's fiscal year 2008, combined revenues are expected to be over $1.7 billion, with combined earnings per share in the range of $2.35 to $2.40.