Sterling Clearing Corporation's default waterfall has the following resources in order: (1) defaulter's initial margin of $1.8B, (2) defaulter's default fund contribution of $300M, (3) CCP skin-in-the-game of $500M, (4) mutualized default fund of $4B, (5) assessment powers up to $2B. If a clearing member defaults with total losses of $2.9B, how much of the mutualized default fund (layer 4) is consumed?