In the news on its website announcing the hiring of Felipe Massa as its driver in 2014, there was a photo of the driver in the back where a panel appear with logos of the Bank of Brazil.
The Bank of Brazil is one of the largest brazilian banks, and during 2012 and 2013 sponsored driver Felipe Nasr in GP2. Nasr is appointed as reserve driver for Williams in 2014, and could take with him (also in the interest of the bank to have his image associated with the image of Massa) for the sponsorship team.
The site Grande Prκmio (www.grandepremio.com.br) first to report the hit Massa with Williams, takes it for granted that the bank will be a sponsor of Williams in 2014.
Looking at the layout of Carlin (GP2) in 2013, gives to dream with a retro paint in Williams, recalling the years 1985-1993.