The key ethical principles in this case relate to the relationship that the practitioner has with the client, and how they act on this situation and how they use the information that they are privy to. The relationship between any licensed medical professional, of which a psychologist is one, and their client should be treated as confidential at all times, and the information flow between these two entities should be kept as confidential as well. If the psychologist uses any information gained through the process of carrying out the duties that they have been paid for by the client then they should keep that information confidential. In this case the psychologist becomes aware of information about the company they have been hired by.
If that information is used by the psychologist to benefit personally, and this action is discovered, the psychologist may end up with some kind of malpractice lawsuit, if anyone objects or they have committed an offence. The psychologist has a dilemma to deal with, as the information is mere speculation, and is not guaranteed to produce extra profits for the company, or even produce better returns for investors.
The strategy of the psychologist in this case may be based on their own ethics, due to the fact they are not sure to use the information or not, nor are they sure the information may be profitable either. Should they choose to use this information, then it has set a precedent for their business practices, and if another situation arose where they could use confidential information for their own benefit then they may be less ethical about using this information.
Therefore this situation may not be as clear cut as it seems due to the speculation involved, and the information not being supported by hard evidence. The information is the view of a certain individual whose has no external verifiable source and has no clear evidence to back it up. This point, that the information has not been corroborated or verified, means the psychologist is within their rights, and can consider using it for their own benefit, without breaking any ethical standards of business behavior. This may be different if the contract between the software manufacturer and the psychologist stipulates that confidentiality must be maintained at all times.