Quote from mcurto:
... Yes, PIMCO is always selling premium in the various CBOT options pits, most of it has been centered in the 10yr options the last two years or so since the liquidity is absolutely enormous. Their initial June strangle position started out as the June 107-111 (identical to their March which expired worthless) but eventually shifted to this June 105-109 strangle as we sold off. On top of this strangle, they also sell options outside of those levels, so sell any calls above the 109 strike that aren't already worthless and sell any puts below the 105 strike that aren't already worthless. For the past month it has been like clockwork, they sell exactly 5000 of the June strangles every day, and that adds up to a pretty significant position by expiration.