The Capitol Hill Challenge stock-market competition for schools is run by the SIFMA Foundation, an educational nonprofit arm of the Securities Industry and Financial Markets Association.
Cheung writes in a research note that estimates on Baidu are likely to move lower given increased competition, a weaker than expected ad market and mobilization challenge on mobile devices.
Analysts say the entry into the market by BT represents a serious challenge, despite Sky's success in fighting off previous competition from the likes of ITV Digital, Setanta and ESPN.
The HarperCollins negotiations with Apple represent a direct challenge to Amazon, which dominates the fast-growing e-book market but which could face significant competition from an Apple tablet.
The mix of personality, drive and innovation in business leaders mixed with market demand, the economy, competition, government and the world around us makes for a fresh challenge requiring fresh approaches every day.