The comment thread to the post below on SEC v. Rocklage raises the question of whether insider trading harms investors. My answer is: no.
Here's what I wrote in my short treatise Securities Law-Insider Trading:
An investor who trades in a security contemporaneously with insiders having access to material nonpublic information likely will allege injury in that he sold at the wrong price; i.e., a price that does not reflect the undisclosed information. If a firm’s stock currently sells at $10 per share, but after disclosure of the new information will sell at $15, a shareholder who sells at the current price thus will claim a $5 loss.
The investor’s claim, however, is fundamentally flawed. It is purely fortuitous that an insider was on the other side of the transaction. The gain corresponding to the shareholder’s loss is reaped not just by inside traders, but by all contemporaneous purchasers whether they had access to the undisclosed information or not.
To be sure, the investor might not have sold if he had had the same information as the insider, but even so the rules governing insider trading are not the source of his problem. On an impersonal trading market, neither party knows the identity of the person with whom he is trading. Thus, the seller has made an independent decision to sell without knowing that the insider is buying; if the insider were not buying, the seller would still sell. It is thus the nondisclosure that causes the harm, rather than the mere fact of trading.
The information asymmetry between insiders and public investors arises out of the mandatory disclosure rules allowing firms to keep some information confidential even if it is material to investor decision-making. Unless immediate disclosure of material information is to be required, a step the law has been unwilling to take, there will always be winners and losers in this situation. Irrespective of whether insiders are permitted to inside trade or not, the investor will not have the same access to information as the insider. It makes little sense to claim that the shareholder is injured when his shares are bought by an insider, but not when they are bought by an outsider without access to information. To the extent the selling shareholder is injured, his injury thus is correctly attributed to the rules allowing corporate nondisclosure of material information, not to insider trading.
Arguably, for example, the TGS shareholders who sold from November through April were not made any worse off by the insider trading that occurred during that period. Most, if not all, of these people sold for a series of random reasons unrelated to the trading activities of insiders. The only seller we should worry about is the one that consciously thought, “I’m going to sell because this worthless company never finds any ore.” Even if such an investor existed, however, we have no feasible way of identifying him. Ex post, of course, all the sellers will pretend this was why they sold. If we believe Manne’s argument that insider trading is an efficient means of transmitting information to the market, moreover, selling TGS shareholders actually were better off by virtue of the insider trading. They sold at a price higher than their shares would have commanded but for the insider trading activity that led to higher prices. In short, insider trading has no “victims.” What to do about the “offenders” is a distinct question analytically.
A more sophisticated argument is that the price effects of insider trading induce shareholders to make poorly advised transactions. It is doubtful whether insider trading produces the sort of price effects necessary to induce shareholders to trade, however. While derivatively informed trading can affect price, it functions slowly and sporadically. Given the inefficiency of derivatively informed trading, price or volume changes resulting from insider trading will only rarely be of sufficient magnitude to induce investors to trade.
Assuming for the sake of argument that insider trading produces noticeable price effects, however, and further assuming that some investors are misled by those effects, the inducement argument is further flawed because many transactions would have taken place regardless of the price changes resulting from insider trading. Investors who would have traded irrespective of the presence of insiders in the market benefit from insider trading because they transacted at a price closer to the correct price; i.e., the price that would prevail if the information were disclosed. In any case, it is hard to tell how the inducement argument plays out when investors are examined as a class. For any given number who decide to sell because of a price rise, for example, another group of investors may decide to defer a planned sale in anticipation of further increases.
