I’m not exactly sure what you mean by “defensible”. It’s true that some anomalies evaporate almost immediately once they are noticed, but others persist long after that—even for decades.
One notable example of a long-lived inefficiency was the capping of the Euro/Franc rate at 1.20 from 2011 to 2015. This was announced publicly by the Swiss National Bank so it was available information. A price cap is a glaring market inefficiency, exploitable with a simple grid strategy. If the EMH were true, the rate should have settled at 1.20 almost instantly, but in fact, it took about three years for this to happen. And Forex is about as liquid as markets get.
I’m not exactly sure what you mean by “defensible”. It’s true that some anomalies evaporate almost immediately once they are noticed, but others persist long after that—even for decades.
One notable example of a long-lived inefficiency was the capping of the Euro/Franc rate at 1.20 from 2011 to 2015. This was announced publicly by the Swiss National Bank so it was available information. A price cap is a glaring market inefficiency, exploitable with a simple grid strategy. If the EMH were true, the rate should have settled at 1.20 almost instantly, but in fact, it took about three years for this to happen. And Forex is about as liquid as markets get.