>>12375224Assuming complete information for all parties, yes. In practice, it's kind of a mixed bag. I'm not convinced that in the stock market that shares prices perfectly reflect the time discounted expected value of the company's / share value, partly because all investors are working with potentially incomplete and asymmetric information regarding the asset, coupled this with some behavioral finance wonky stuff and I think its hard to say the price is right. However, I do believe that most types of arbitrage are eaten up by HFT groups that keep the prices correct in that sense.
Short version, I think that markets are generally not efficient in the sense that they reflect the correct price but yes in that in the short term there are no "free lunches" and the only way to beat the market is to either have better/more accurate data and models.
