Brendan Kennedy and Michael Blue, private-equity financiers, settled into a downtown Seattle conference room in March to meet with a start-up. Both wore charcoal blazers and polished loafers. Kennedy, 41, is the former chief operating officer of SVB Analytics, an offshoot of Silicon Valley Bank. Blue, 35, learned his trade at the investment-banking firm de Visscher & Co. in Greenwich, Conn. Two years ago they quit comfortable posts to form Privateer Holdings, a firm that operates on the Kohlberg Kravis Roberts model: they buy companies using other people’s money and try to increase their value. What sets them apart is the industry in which they invest. Privateer Holdings is the first private-equity firm to openly risk capital in the world of weed. Or as the Privateer partners prefer to call it, “the cannabis space.”