CALGARY, ALBERTA--(Marketwire - Sept. 20, 2012) -

NOT FOR DISTRIBUTION TO U.S. NEWSWIRE SERVICES OR FOR DISSEMINATION IN THE U.S.

TransAlta Corporation (TransAlta) (TSX:TA)(NYSE:TAC) announced today that under its common share offering that closed on September 13, 2012, the underwriters, exercised in part their over-allotment option to purchase an additional 1,992,000 common shares at the offering price of $14.30 per common share.

Including this option exercise, the offering resulted in a total of approximately 21.24 million common shares issued for total gross proceeds of approximately $304 million. The net proceeds from the offering will be used to, fund growth capital expenditures, including the partial funding of the previously announced Solomon power station acquisition if completed, repay short term indebtedness, and for general corporate purposes.

The Common Shares were offered through a syndicate of underwriters led by CIBC and RBC Capital Markets, and including Scotiabank, TD Securities Inc., BMO Capital Markets, National Bank Financial Inc., Bank of America Merrill Lynch, HSBC Securities (Canada) Inc., Canaccord Genuity Corp. and Desjardins Securities Inc., by way of a prospectus supplement to TransAlta's short form base shelf prospectus dated November 15, 2011.

About TransAlta Corporation

TransAlta is a power generation and wholesale marketing company focused on creating long-term shareholder value. TransAlta maintains a low-to-moderate risk profile by operating a highly contracted portfolio of assets in Canada, the United States and Australia. TransAlta's focus is to efficiently operate our geothermal, wind, hydro, natural gas and coal facilities in order to provide our customers with a reliable, low-cost source of power. For 100 years, TransAlta has been a responsible operator and a proud contributor to the communities where we work and live. TransAlta is recognized for its leadership on sustainability by the Dow Jones Sustainability North America Index, the FTSE4Good Index and the Jantzi Social Index. TransAlta is Canada's largest investor-owned renewable energy provider.

This news release may contain forward looking statements, including statements regarding the business and anticipated financial performance of TransAlta Corporation and the anticipated use of the proceeds of the offering. These statements are based on TransAlta Corporation's belief and assumptions based on information available at the time the assumption was made. These statements are subject to a number of risks and uncertainties that may cause actual results to differ materially from those contemplated by the forward-looking statements. Some of the factors that could cause such differences include, pricing in the market place, our inability to enter into long term contracts due to prevailing market conditions, legislative or regulatory developments, competition, global capital markets activity, changes in interest rates, currency exchange rates, inflation levels and general economic conditions in geographic areas where TransAlta Corporation operates.

Note: All financial figures are in Canadian dollars unless noted otherwise.

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