(Premarket story updated to reflect share prices changes and more stock news)

NEW YORK ( TheStreet) -- Shares of Chinese power generation systems provider A-Power Energy ( APWR ) tanked by 20.6% to $5.05 in premarket trading after the company reduced its full-year revenue guidance to $310 million from a previously expected $500 million, and cut its net income forecast to $50 million from a previously expected $60 million.

A-Power cited softness in the wind energy business and a shortage of turbine purchases from the company.

Shares of Royal Bank of Scotland ( RBS) rose 4.7% to $12.31 before the market open as the company announced it has completed the sale of its Global Merchant Services business to an investment consortium consisting of Advent International and Bain Capital,. RBS maintains a minority stake in the new GMS business to be called WorldPay.

Shares of India-based automaker Tata Motors ( TTM) rose 3.3% to $33.80 in premarket trading after reporting a 1% increase in November sales to 54,622 units from 54,108 the same period last year.

Shares of German conglomerate Siemens ( SI) advanced by 3.5% to $113.63 in premarket trading. Dow Jones reports the company plans on ramping up market share in city infrastructure after an interview with Siemens strategy chief Roland Busch.

Dow Jones also reported Siemens has won approval for its bid to install the control offices of the Berlin-Brandenburg international airport.

State Street ( STT - Get Report) said late Tuesday it was cutting 1,400 jobs, or 4% of its work force, as part of a restructuring plan.

Shares ended Tuesday's trading session down 1.1% at $43.20.

Chinese lithium battery maker Advanced Battery Technologies ( ABAT) plans to raise $30 million in fresh capital through a dilutive stock sale. The news sent shares tumbling; the stock was adding 2.4% to $3.88 in premarket trading.

Youth specialty retailer Aeropostale ( ARO) reports third-quarter earnings Wednesday. Wall Street is calling for earnings of 66 cents a share on revenue of $605.98 million. The stock rose 1.7% to $27.50 before the market open. TEXT

Banco Santander ( STD) shares took a tumble Tuesday afternoon on concerns that it would require a financial bailout. Shares have regained traction in premarket trading, rising 5.9% to $10.19.

The European Commission on Tuesday said it turned down a request by ING ( ING) to redeem a $1.5 billion hybrid capital instrument from private investors, the Wall Street Journal reported. Although shares ended down 5.1% to $8.84 at Tuesday's closing bell, they're gaining traction before the bell on Wednesday, higher by 5.2% to $9.30.
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-- Written by Andrea Tse in New York.

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