by other companies. The following table provides net debt as of December 31, 2014 and 2013.

  

In 2014, net debt increased by $2.3 billion to a net debt balance of $3.5 billion (as of December 31, 2014), as 3M progressed on its capital structure strategy and experienced higher debt levels and lower cash balances in both the U.S. and internationally. Specific actions related to cash, cash equivalents, and marketable securities, in addition to debt, are discussed further below.

 

Cash, cash equivalents and marketable securities:

 

At December 31, 2014, 3M had $3.4 billion of cash, cash equivalents and marketable securities, of which approximately $3.3 billion was held by the Company’s foreign subsidiaries and less than $100 million was held by the United States. Of the $3.3 billion held internationally, U.S. dollar-based cash, cash equivalents and marketable securities totaled $1.9 billion, or 58 percent, which was invested in money market funds, asset-backed securities, agency securities, corporate medium-term note securities and other high quality fixed income securities. At December 31, 2013, cash, cash equivalents and marketable securities held by the Company’s foreign subsidiaries and in the United States totaled approximately $4.3 billion and $0.5 billion, respectively.



The Company’s total balance of cash, cash equivalents and marketable securities was $1.4 billion lower at December 31, 2014 when compared to December 31, 2013. 3M was able to manage the business with lower cash levels, particularly in the U.S., due to significant ongoing cash flow generation and proven access to capital markets funding throughout business cycles.

 

Total debt:

 

The Company’s total debt was $0.8 billion higher at December 31, 2014 when compared to December 31, 2013. The strength of 3M’s capital structure and significant ongoing cash flows provide 3M proven access to capital markets. Additionally, the Company’s maturity profile is staggered to help ensure refinancing needs in any given year are reasonable in proportion to the total portfolio. As of February 2015, the Company has an AA- credit rating, with a stable outlook, from Standard & Poor’s and an Aa3 credit rating, with a negative outlook, from Moody’s Investors Service. The Company’s ongoing transition to a more optimized capital structure, financed with additional low-cost debt, could impact 3M’s credit rating in the future.

 

Effective May 16, 2014, the Company updated its “well-known seasoned issuer” shelf registration statement, which registers an indeterminate amount of debt or equity securities for future sales. This replaced 3M’s previous shelf registration dated August 5, 2011. In June 2014, in connection with the May 16, 2014 shelf registration, 3M re-commenced its medium-term notes program (Series F) under which 3M may issue, from time to time, up to $9 billion aggregate principal amount of notes. Included in this $9 billion are $2.25 billion of notes previously issued in 2011 and 2012 as part of Series F.

 

Significant long-term debt activity during 2013 is summarized below:

 

∙                  In August 2013, 3M repaid $850 million (principal amount) of medium-term