Aditya Birla ARC Limited is set to make a formal bid for RattanIndia Power Limited (BSE:533122). Aditya Birla ARC is also looking at the option to partner Goldman Sachs and Rajiv Rattan, to make the bid, a source from a leading bank said. Lenders are expecting an offer from the ARC by January 21, 2019. They are expected to take a decision by February 1, 2019. The banks are likely to take a hit of 50% on its exposure to the Maharashtra, Amravati-based project that generates 1,350 Mw of electricity.