The short answer is no. Inside information is only public when, in the words of Prof. Donald Langevoort, “the market has internalized it.”
Courts have recognized for decades that releasing the information to the market doesn’t mean it is instantly “public” for insider trading purposes. In SEC v. Texas Gulf Sulphur, 401 F.2d at 854 n. 18 (2d Cir. 1968), the Second Circuit said:
[W]e note in passing that, where the news is of a sort which is not readily translatable into investment action, insiders may not take advantage of their advance opportunity to evaluate the information by acting immediately upon dissemination.
This was merely dicta, since in Texas Gulf Sulphur, no insiders who were actually before the court traded in securities after the release of the information. However, trial courts generally adopted this approach when it actually mattered. For example, in Shapiro v. Merrill Lynch, certain insiders were trading in shares of Douglas Aircraft with the inside knowledge that the company was about to announce unexpectedly disappointing earnings. The court evaluated insider trading claims by people who bought shares on the day of the release (which was carried over the wire sometime before trading opened). The court said:
There is no doubt that those investors who purchased Douglas stock after public dissemination of the new earnings report do not have a cause of action against defendants. A question arises, however, as to just when such dissemination is accomplished. It is rather doubtful that disclosure is instantaneously achieved upon release of the information to the press.
The same court added:
Conceivably, the news ticker could have carried Douglas’ press release at one minute prior to the opening of the exchange and plaintiffs M. Shapiro, I. Shapiro, Naigles and Saxe could have placed their orders at one minute after the opening. It could not be said, in that event, that full disclosure had been achieved within two minutes of its release.
So, at the very least, in the 1960s, two minutes wasn’t enough time after dissemination to deem the information “public.” There isn’t a precise bright line test for when the market has internalized the information. Courts typically look at when the trading price and volume of the stock “levels off” to the new normal level after “the news had been fully digested and acted upon by investors.” See SEC v. MacDonald, 699 F2d 47 (1st Cir. 1983).
This is true. But, in SEC v. MacDonald, the court also said, “[W]e do not depart from the principle that doubts [about when information is really public] are to be resolved against the defrauding party.”