Quote from kut2k2:
I believe we're basically in agreement here. I wasn't arguing that price has no random component; that would be silly. My attack was on random walk, which says that price is fundamentally random, even with a drift component. You and I both recognize the serial correlations, which are anathema to random walkers.
I'd be hard pressed to find anyone (academic or otherwise) who actually believes in strong, classic random walk. Sure, we use iid random walk for some derivatives pricing for matter of analytical simplicity, but I don't think anyone thinks its right. Sometimes it just doesn't matter that much.
