Since the beginning of 2007, 497 private equity investors have closed a total of 616 U.S.-based buyout funds, according to the PitchBook Platform. 70 of those funds closed this year on an aggregate of more than $69 billion of committed capital. This year, billion dollar buyout funds are making a comeback. With 21 funds having closed on at least $1 billion in 2012 to date, billion dollar funds now account for 30% of the U.S. buyout funds closed so far this year, their second highest share ever, after the 38% share posted in 2009. That being said, extremely large funds are still a rarity, as only one fund of $5 billion or more has closed so far in 2012: Leonard Green & Partners' $6.25 billion Green Equity Investors VI fund, which closed in May.