Imagine if Warren Buffett of 1960 puts down the deadtree 10-K he got in the mail and time travels forward to 2019. Then he looks over the shoulder of an analyst at present day O’Shaughnessy Asset Management. He would find the scene unrecognizable.
Or, if the original Jesse Livermore time traveled from the 1920s stock exchange to the present day trading floor of DE Shaw or Renaissance. Again, completely unrecognizable.
Back in the day people went to the SEC office in the Washington DC to access annual reports faster. That was how one got a fundamental edge. Now people scrape filings the minute they come out. Or use satellites and credit card data to get an edge on information before it hits regulatory filings. People used to gauge momentum by looking at the facial expressions of other traders, now they use complex computer models. People mine market and fundamental data around the globe looking for a bit of an edge. New techniques, same thing.
Over time there is the change in the physical activities, and words we use to describe the process of identifying and exploiting market inefficiencies. Nonetheless the ecological function is the same. Investors are just looking for mispriced risk, and exploiting it till its no longer mispriced.
Around the world there are unfair coins waiting for someone to flip them. Arbitrageurs will need to use weirder and weirder methods to find and exploit them. Methods change, but the arb remains the same.