in film manufacturing assets for optical systems and other non-optical businesses which use similar technology. Also, in 2010, 3M increased capacity at its multi-purpose manufacturing facility in Singapore and invested in optical film capacity in Korea. Lastly, in 2010, investments in the Industrial and Transportation business included solar energy in the U.S. and industrial adhesives and tapes in China. In 2009, in response to then-difficult global economic conditions, the Company reduced its capital spending significantly.

 

Refer to Note 2 for information on acquisitions. The Company is actively considering additional acquisitions, investments and strategic alliances, and from time to time may also divest certain businesses.

 

Purchases of marketable securities and investments and proceeds from sale (or maturities) of marketable securities and investments are primarily attributable to asset-backed securities, agency securities, corporate medium-term note securities and other securities, which are classified as available-for-sale. Interest rate risk and credit risk related to the underlying collateral may impact the value of investments in asset-backed securities, while factors such as general conditions in the overall credit market and the nature of the underlying collateral may affect the liquidity of investments in asset-backed securities. The coupon interest rates for asset-backed securities are either fixed rate or floating. Floating rate coupons reset monthly or quarterly based upon the corresponding monthly or quarterly LIBOR rate. Each individual floating rate security has a coupon based upon the respective LIBOR rate +/- an amount reflective of the credit risk of the issuer and the underlying collateral on the original issue date. Terms of the reset are unique to individual securities. Fixed rate coupons are established at the time the security is issued and are based upon a spread to a related maturity treasury bond. The spread against the treasury bond is reflective of the credit risk of the issuer and the underlying collateral on the original issue date. 3M does not currently expect risk related to its holdings in asset-backed securities to materially impact its financial condition or liquidity. Refer to Note 9 for more details about 3M’sdiversified marketable securities portfolio, which totaled $2.357 billion as of December 31, 2011. Additional purchases of investments include additional survivor benefit insurance and equity investments.

 

Cash Flows from Financing Activities:

  

Total debt at December 31, 2011 was $5.2 billion, compared to $5.5 billion at year-end 2010 and $5.7 billion at year-end 2009. Total debt was 25 percent of total capital (total capital is defined as debt plus equity) at both year-end 2011 and year-end 2010, compared with 30 percent at year-end 2009. The net change in short-term debt is typically due to commercial paper activity and international borrowings. In 2011, major items in repayment of debt (maturities greater than 90 days) included redemption of $800 million (principal amount) of medium-term notes in November 2011, redemption of Convertible Notes, repayment of debt related to the 11.6