The US Stockmarket switch from fractions to decimals gives an edge to market specialists competing with institutional investors. If an institutional investor bids $50 for 100,000 shares of a company, a specialist can up the bid by a penny, prompting the large investor to move up a couple more cents. The specialist walks away with a profit from the spread. How will this affect the market? We will probably see a continuation of large jumps in stock prices, typical of our age. But is this good or bad?

Reference: Penny shake-up for US markets (BBC)