[Nelson69]

It's as old as time...

Eamon Javers' book Broker, Trader, Lawyer, Spy covers some cases of this sort of thing. One I can easily remember is a hedge fund flew private planes around taking areal photos near power plants. Coal fire power plants store their fuel out in the open and they buy it by the train-load, so they were able to time the market based upon when power plants were going to make large coal purchases, as they do it when their piles of coal reach a certain size. I don't remember the numbers quoted in the book but they made money doing this, it was a couple percent.

It's only unfair if you think your 401k or personal trading account is/can/will grow anything like what hedge funds do. This coal market manipulating fund, they put money in, flying planes around and taking pictures isn't free, then they did analysis on the pictures which wasn't free, then they put real money in to the market to bet on it moving a certain way... which they are really only allowed to do because there is a counter-party that is willing to take that bet on. If it were really egregious, you could argue that the folks buying energy at incrementally higher rates are getting the shaft and that's not really fair but their energy provider could be smarter about when it orders up fuel. Once it goes public, the players and market tend to react to it

[throwaway2048]

There is a (likely apocryphal) story that when Galileo presented the Doge of Venice with his first telescope, he took him aside privately and they went to the tallest tower in Venice to spy on the incoming trade vessels, then rushed down to the market and proceeded to make a killing on the knowledge of when exactly cargo would be arriving.

[drited]

And another about how the Rothchilds had a better messaging system (flags? Burning pyres? Pigeons?) after the of the battle of Waterloo and traded British Government bonds on the London exchange after the win (first openly selling to head fake the market which knew of their messaging time advantage and then buying through nominees in the ensuing panic)