(Sharecast News) - Crest Nicholson executive chairman Stephen Stone purchased 150,000 ordinary shares in the FTSE 250 housebuilder on Monday.Stone, who joined Crest Nicholson back in January 1999, acquired the shares at an average price of 302.90p each, for a total value of £454,350.01.Crest Nicholson warned investors last week that full-year profits would be lower than expected and that margins would be below previous guidance, as it announced the departure of its chief financial officer.In a pre-close trading update, the company said the market environment for new homes in London and at higher price points in the South of England has been more difficult than previously anticipated, where sales have not picked up during the traditionally stronger early autumn selling season.Executive chairman Stephen Stone said: "The usual autumn pick up in sales volumes has not been evident during September and October, with many customers putting off decisions to buy whilst current political and economic uncertainties persist."Discussing the warning, broker Shore Capital said the issue was the same as in previous warnings, namely a very tough market at higher price points, especially beyond the limits of help to buy, and problems completing sales where buyers also need to sell a house in the second-hand market."The problem is really one of affordability although the industry is keen to blame Brexit," said ShoreCap's Robin Hardy, noting that Bellway earlier in the week acknowledged that Brexit actually barely registers outside London, "so we still believe that that is not the core of the issue for the house builders but a raw lack of affordability".Crest Nicholson also revealed that chief financial officer Robert Allen would be stepping down from the board and leave the company after a short handover period. Patrick Bergin will take on the CFO responsibilities until a replacement for Allen is found.As of 16015 BST, Crest shares were up 1.78% to 308.20p.Top Director BuysCrest Nicholson Holdings (CRST)Director name: Stone,StephenAmount purchased: 150,000 @ 302.90pValue: £454,350.01Wishbone Gold (WSBN)Director name: Poulden,RichardAmount purchased: 156,301,312 @ 0.11pValue: £171,931.44Crest Nicholson Holdings (CRST)Director name: Walle,Leslie Van deAmount purchased: 20,000 @ 305.37pValue: £61,074.00Ite Group (ITE)Director name: Shashoua,MarkAmount purchased: 80,000 @ 60.55pValue: £48,440.00Altus Strategies (ALS)Director name: Poulton,StevenAmount purchased: 795,431 @ 3.22pValue: £25,612.88Wishbone Gold (WSBN)Director name: Harrison,Jonathan CharlesAmount purchased: 19,924,582 @ 0.11pValue: £21,917.04Wishbone Gold (WSBN)Director name: Gravett,Alan David Amount purchased: 19,886,236 @ 0.11pValue: £21,874.86Renishaw (RSW)Director name: Chesney,CarolAmount purchased: 500 @ 3,781.00pValue: £18,905.00Wishbone Gold (WSBN)Director name: Mainelli,Michael RaymondAmount purchased: 16,098,409 @ 0.11pValue: £17,708.25Scotgold Resources (di) (SGZ)Director name: Roux,Nathaniel le Amount purchased: 50,000 @ 25.00pValue: £12,500.00C4x Discovery Holdings (C4XD)Director name: Fox,CraigAmount purchased: 5,900 @ 86.70pValue: £5,115.30Altus Strategies (ALS)Director name: Grainger,MatthewAmount purchased: 50,000 @ 4.00pValue: £2,000.00Rotork (ROR)Director name: Davis,JonathanAmount purchased: 472 @ 304.58pValue: £1,437.62Amur Minerals Corporation Npv (AMC)Director name: Young,Robin JayAmount purchased: 15,010 @ 4.10pValue: £615.41Amur Minerals Corporation Npv (AMC)Director name: Savage,Brian CharlesAmount purchased: 15,010 @ 4.10pValue: £615.41Amur Minerals Corporation Npv (AMC)Director name: Naumovski,LjupcoAmount purchased: 15,010 @ 4.10pValue: £615.41Amur Minerals Corporation Npv (AMC)Director name: Swanson,JackAmount purchased: 15,009 @ 4.10pValue: £615.37Amur Minerals Corporation Npv (AMC)Director name: Gazzard,Paul Amount purchased: 15,009 @ 4.10pValue: £615.37Amur Minerals Corporation Npv (AMC)Director name: McKay,Paul Amount purchased: 15,009 @ 4.10pValue: £615.37Amur Minerals Corporation Npv (AMC)Director name: Schafer,Robert WilliamAmount purchased: 15,009 @ 4.10pValue: £615.37Rockrose Energy (RRE)Director name: Pawson,Steve Amount purchased: 37 @ 409.33pValue: £151.45Rockrose Energy (RRE)Director name: Austin,AndrewAmount purchased: 37 @ 409.33pValue: £151.45Rockrose Energy (RRE)Director name: Morrow,JohnAmount purchased: 37 @ 409.33pValue: £151.45Rockrose Energy (RRE)Director name: Benmore,RichardAmount purchased: 37 @ 409.33pValue: £151.45Arden Partners (ARDN)Director name: Clive Reed-Daunter,James (Jim)Amount purchased: 441 @ 34.01pValue: £149.98Arden Partners (ARDN)Director name: Brown,Donald Amount purchased: 441 @ 34.01pValue: £149.98Mitchells & Butlers (MAB)Director name: Jones,Timothy (Tim) CharlesAmount purchased: 54 @ 259.20pValue: £139.97Mitchells & Butlers (MAB)Director name: Urban,PhilAmount purchased: 53 @ 259.20pValue: £137.38Mitchells & Butlers (MAB)Director name: McMahon,Greg Amount purchased: 39 @ 259.20pValue: £101.09Top Director SellsRicardo (RCDO)Director name: Shemmans,DaveAmount sold: 19,685 @ 772.00pValue: £151,968.20Ricardo (RCDO)Director name: Garrett,MarkAmount sold: 8,452 @ 772.00pValue: £65,249.44Ricardo (RCDO)Director name: Gibson,IanAmount sold: 4,713 @ 772.00pValue: £36,384.36