Hopefully you won't need the $15 billion in a single year. So it should be probably invested in some form of diversified portfolio, with a component of very safe, fixed-return assets, like Government of Canada one- to three-year bonds, for example, for at least part of it. Another part could be invested in T-bills and another part could be invested in things that would probably bring a little more income. It would be diversified, basically.
