If markets are efficient, you will never make profitable trades as a result of reading the Financial Times. Efficient markets move quickly and respond to any new headlines – disappointing earnings, a cut in interest rates, a fraud or a safety incident. Markets will sometimes overreact, drifting backwards after a lurch, or underreact, taking time to digest the true impact of the new information – but overreactions and underreactions should balance out. And when no news is available, the prices of an efficient market won’t change much.

But do markets really react efficiently to news? It would be easy to tell if it were easy to identify all genuine news. Sadly, it is not. Yet two inventive new academic papers claim to have solved the problem of identifying news, in two very different contexts. The studies could not be more unalike. One looks second-by-second at trading data from one of the world’s most active financial exchanges. The other analyses market information that is more than two centuries old.