The wife of Admiral's Chief Executive Officer (CEO) bought a staggering amount of shares in the car insurance giant on Tuesday, worth nearly 1.6m pounds.Diane Briere de l'Isle, the partner of CEO Henry Engelhardt, snapped up 144,348 shares in Admiral at average price of 1,107p - this cost her a total of £1,597,932.Following this transaction, 'Henry Engelhardt and Family' holdings now total 37,957,913 ordinary shares in the insurer, equal to just under 14% of the entire issued share capital.The purchase came just a few days after Admiral's first-half results, in which it reported a 7% rise in pre-tax profit to £171.8m and a 6% increase in group turnover to £1.17bn. However, the share price has been under pressure since the figures were released on August 30th, falling around 5%.Speaking at the time of the results, Engelhardt said: "In the UK, following the very significant growth in 2010 and 2011, we continue to slow our rate of growth to a more modest level, which we believe is a sensible response to the increased competition in the market."Credit Suisse downgraded its rating for the stock from 'outperform' to 'neutral' on Monday, saying that despite the solid headline result, "weaker-than-expected vehicle count growth, heightened pressure on industry pricing and larger-than-expected international losses have prompted us to lower earnings forecasts by 4-7% for FY12-14e." Top Director BuysAdmiral Group (ADM) Director name: Mr Henry EngelhardtAmount purchased: 144,348 @ 1,107.00p Value: £1,597,932Bank of America Corp. (BAC) Director name: Mr Sharon L AllenAmount purchased: 14,153 @ $7.99 Value: $113,082Bank of America Corp. (BAC) Director name: Mr Jack O Bovender JrAmount purchased: 14,153 @ $7.99 Value: $113,082Bank of America Corp. (BAC) Director name: Mr R David YostAmount purchased: 14,153 @ $7.99 Value: $113,082Bank of America Corp. (BAC) Director name: Ms Linda P Hudson Amount purchased: 14,153 @ $7.99 Value: $113,082Innovation Group (TIG) Director name: Mr David ThorpeAmount purchased: 250,000 @ 20.15p Value: £50,375Compass Group (CPG) Director name: Ms Susan MurrayAmount purchased: 3,000 @ 701.29p Value: £21,039Ladbrokes (LAD) Director name: Mr Ian BullAmount purchased: 12,200 @ 170.45p Value: £20,795Top Level Domain Holdings Ltd. (DI) (TLDH) Director name: Mr David de Jongh WeillAmount purchased: 250,000 @ 5.00p Value: £12,500Top Director SellsEuromoney Institutional Investor (ERM) Director name: Mr Dan C CohenAmount sold: 25,000 @ 752.00p Value: £188,000