Star Tribune 100: Comings and goings

The biggest additions to the Star Tribune 100 this year are not new companies but acquisitions by some of our biggest companies. The biggest deals last year include:

• Pentair (No. 17), which more than doubled in size through a $4.5 billion acquisition of the flow control business of Tyco International. The deal has already doubled the number of Pentair employees from 15,000 to 30,000. Once the books are integrated, Pentair's total revenue should top $7 billion. Technically, Pentair is based in Switzerland, but operations and corporate officers remain in Minnesota, and we'll keep them on our list as long as that is the case.

• No. 1-ranked UnitedHealth Group landed the second-largest Minnesota deal in 2012 and also entered the Brazilian health care market with the $4.3 billion acquisition of health insurer and hospital operator Amil Participações.

• Ecolab Inc. (No. 9), which closed its $8.3 billion acquisition of Nalco Holding Co. in December 2011, made its second-largest acquisition in October, buying energy services firm Champion Technologies for $2.3 billion. The deal closed on Feb. 28 and is expected to add another $1.4 billion in annual sales and approximately 3,300 more employees.

• Alliant Techsystems Inc. (No. 17 last year) moved its headquarters to Virginia in 2012 to be closer to its largest customer, the U.S. Department of Defense, and the cluster of other defense contractors surrounding Washington, D.C.

• Fair Isaac announced it was moving its corporate headquarters back to California, where the company was founded. The company's new headquarters is in San Jose "to take advantage of technology innovations in big data and cloud computing,'' the company said. The deal was announced in January, so we've kept them on the list, No. 38, for one more year.

• Caribou Coffee (ranked No. 51 last year) was acquired by JAB Beech Inc., a member of the Joh. A. Benckiser Group. The $340 million deal was completed Jan. 24, but Caribou is not reporting annual results for 2012, so it is off the list.

• FSI International (No. 67 last year), the Chaska company that made semiconductor production equipment, was acquired by Tokyo Electron on Oct. 12 for $252 million. FSI's small size made it increasingly difficult to compete in the global market for computer chip manufacturing.

• Music notation software maker MakeMusic has been on the fringes of the Star Tribune 100 for years, and the company, which ranked 91st this year, will be gone next year as LaunchEquity Partners completed an acquisition of the company on May 1.

There were two IPOs in 2012: one a real estate investment trust, the other a February offering by Proto Labs. We were able to include the Maple Plain-based quick-turn manufacturer of custom parts in time for last year's list, and this year it rose eight spots from 68 to 60 in its first full year as a publicly traded company.

We added Tile Shop Holdings, which became a public company after the merger with a shell company, JWC Acquisition Corp., on Aug. 21. Tile Shop also completed a secondary offering on Dec. 18. The specialty retailer debuts on our list at No. 58 with $182.7 million in sales.

We'll likely add the latest Minnesota IPO to next year's list. On May 10, BioAmber Inc. completed a unit offering that raised $80 million. The Plymouth-based company is a next-generation chemical company that converts renewable feedstocks into chemicals used as replacements for petroleum-derived plastics and other chemicals. The company has 54 employees, revenue of less than $1 million, and is seeking to build a facility in Sarnia, Ontario, to produce bio-succinic acid.

• Aetrium, which endured a protracted proxy battle last year, may not be on the list much longer. Ranked at No. 100, Aetrium makes reliability testing equipment. It announced on Feb. 27 that it was exploring strategic alternatives.

We've not always included over-the-counter stocks (OTC) on this list, but given the shrinking number of public companies, we've eased our selection criteria. Individuals can buy shares in these OTC companies, but some don't trade actively. This year we've included New Ulm Telecom (No. 82), a phone, video and Internet service provider in Minnesota and Iowa, and Titan Energy Worldwide (No. 90), a provider of backup power generation and energy management needs to businesses.