The bigger the business the more it has to lose, and once a company has risen to the top it will work hard to keep its crown. This might explain why the likes of Google, Facebook and Amazon are hoovering up smaller companies and startups at a rate of knots. It might be that a small startup is a threat to a titan's dominance, or that the bigger company just wants to acquire a standout feature, new technological development or simply more customers. Here are some of the huge sums big companies have paid to acquire smaller rivals...