(ShareCast News) - Sigma Capital chairman David Sigsworth has increased his stake in the company on the same day the residential development group raised £20m in a share placing to build its own portfolio of assets.Sigsworth spent £100,000 buying 133,333 shares at 75p each. He now holds 245,304 shares, or 0.88% of the group's share capital.The company issued on Wednesday 26.7m shares at 75p each, representing a 6.8% discount to the prior's day closing price, and said the proceeds will be invested in a portfolio of private rented assets, which would complement its existing joint ventures with Bank and Grainger.In a separate announcement on Wednesday, the group said the delivery of 927 new rental homes in the North West was ahead of schedule.Top Director BuysSigma Capital Group (SGM) Director name: Mr David SigsworthAmount purchased: 133,333 @ 75.00p Value: £100,000African Potash Ltd (AFPO) Director name: Mr Edward H R MarlowAmount purchased: 6,997,282 @ 0.55p Value: £38,485African Potash Ltd (AFPO) Director name: Mr Jean-Pierre ConradAmount purchased: 2,569,021 @ 0.55p Value: £14,130African Potash Ltd (AFPO) Director name: Dr Simon Dorling Amount purchased: 2,075,000 @ 0.55p Value: £11,412Top Director SellsQinetiQ Group (QQ.) Director name: Mr David MellorsAmount sold: 65,860 @ 235.07p Value: £154,817