TerraForm Power Inc. /zigman2/quotes/205933696/lastsale TERP -5.25% filed Tuesday to boost the value of its stock offering by 50% to $600 million, as the clean power generation company looks to pay for the recently announced acquisition of a European wind and solar power company, Saeta Yield S.A. The price of the offering has not yet been determined. TerraForm had initially filed in March to offer $400 million worth of Class A common stock. The stock slipped 0.1% in morning trade. TerraForm said the offering would be backstopped by Brookfield Asset Management, at a price of $10.66, which is 2.6% below current prices. The company said it will use the proceeds of the stock offering to finance the acquisition of Saeta. On Feb. 7, TerraForm said it had launched a tender to buy 100% of Saeta's outstanding shares. TerraForm's stock has lost 8.4% year to date, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -3.37% has gained 1.0%.