The Financial Times is the hands-down paper of choice for anyone trying to seem clever in a job interview. So it makes sense that to understand its fantastic new 404 error page, you need a highbrow sense of humour and a solid grounding in economic theory.
The 404 page now shows a list of reasons, based on theories you once crammed to pass that Econ elective, why you haven't found a page. Ideas include the Efficient Market Hypothesis (If you had paid enough for the page, it would have appeared), the Speculative Bubble (the page never actually existed and was fundamentally impossible, but everyone bought into it in a frenzy and it's all now ending in tears), and Socialism (If you were to get the page you wanted you might get a better page than someone else, which would be unfair. This way at least everyone gets the same.)
Equally interesting is the process behind the page's creation, explained in detail on the FT Labs blog. In short: the site gets a surprisingly large number of visitors to its 404 page per day (around 4,000), so creating an interesting, non-standard error message made sense. The team tried a number of different concepts: funny (the one you see above), educational, helpful, and competitive. Different pages were served up to different visitors, and they were asked to rank them. This is the internet, so funniness won.