By Elliot Gulliver-Needham Last week, the Unicorn AIM venture capital trust became oversubscribed in just seven days, despite a challenging market for VCTs. The trust opened for offers for a subscription of up to £15m, plus a £5m overallotment facility. In comparison, Enterprise VCT launched in October and closed in 81 days; Octopus AIM VCTs launched in September and closed in 98 days; and the British Smaller Companies VCTs took 149 days to fill. While it seems the days of VCTs selling out in 24 hours are long gone, the seven-day sellout is certainly an oddity in the sector. Unicorn claims inv…