record of generating positive operating income and cash flows. 3M uses the discounted cash flow approach for start-up, loss position and declining businesses, but also uses discounted cash flow as an additional tool for businesses that may be growing at a slower rate than planned due to economic or other conditions.

 

As discussed in Note 17 to the Consolidated Financial Statements, effective in the first quarter of 2010, 3M made certain product moves between its business segments. For those changes that resulted in reporting unit changes, the Company applied the relative fair value method to determine the impact to reporting units. During the first quarter of 2010, the Company completed its assessment of any potential goodwill impairment for reporting units impacted by this new structure and determined that no impairment existed. The discussion that follows relates to the separate fourth quarter 2010 annual impairment test and is in the context of the segment structure that existed at that time.

 

As of September 30, 2010, 3M had 38 primary reporting units, with eight reporting units accounting for approximately 71 percent of the goodwill. These eight reporting units were comprised of the following divisions: 3M Purification Inc., Occupational Health and Environmental Safety, Optical Systems, 3M ESPE, Communication Markets, Industrial Adhesives and Tapes, Security Systems, and Health Information Systems.

 

The fair values for the majority of reporting units were in excess of carrying value by more than 30 percent. The fair values for Optical Systems and 3M Purification Inc., based on fourth quarter 2010 testing, were in excess of carrying value by approximately 23 percent and 26 percent, respectively, with no impairment indicated. As part of its annual impairment testing in the fourth quarter, 3M used a weighted-average discounted cash flow analysis for Optical Systems and 3M Purification Inc., using projected cash flows that were weighted based on different sales growth and terminal value assumptions, among other factors. The weighting was based on management’s estimates of the likelihood of each scenario occurring. In the fourth quarter of 2010, 3M made several larger acquisitions. These acquisitions (with their reporting unit indicated) included Arizant Inc. (Infection Prevention), Cogent Inc. (Security Systems) and Attenti Holdings S.A. (Track and Trace), with goodwill of approximately $512 million, $295 million and $122 million, respectively. Due to the significance of the Cogent Inc. acquisition with respect to its reporting unit, 3M will be monitoring the Security Systems Division in 2011 for any triggering events or other indicators of impairment.

 

In 2010, for those reporting units whose fair value was in excess of carrying value by more than 30 percent, 3M primarily used an industry price-earnings ratio approach, but also used a discounted cash flows approach for certain reporting units. Based on the fair values determined using discounted cash flows for certain reporting units and the industry price-earnings ratio approach for the remaining reporting units, at September 30, 2010, 3M’s implied control premium was