Obviously, the broker is subtly encouraging their clients to buy more stocks. Particularly, when they call with news of stocks that rose more than 10 percents, this will probably motivate people to think the stock is doing well and they want to "get in on the action" while they still can. Even if their calls when a stock goes below 3 percent might encourage some people to sell, the increase of three percents (combined with the 10 percent calls) would definitely be influence to buy.
