Shares of HDFC Asset Management Company tumbled nearly 3 per cent today after its star fund manager Prashant Jain stepped down from the post of chief investment officer. HDFC Asset Management Company stock fell up to 2.76 per cent to Rs 1,872.05 against the previous close of Rs 1,925.10 on BSE. The stock pared some losses and traded 0.84 per cent lower at Rs 1,908 at 2:25 pm.