Group "A" would hold worthless stock and would be out any money they invested.
Group "B" would hold stock of a lesser value and would be out some of the money they invested.
Far from "victimless". And I'm not alone in that opinion:
"...Illegal insider trading is not a victimless crime... Investors who unknowingly trade with people who have inside information lose because they are in an unequal and unfair relationship. Markets where illegal insider trading occurs can suffer a loss of liquidity if international capital flows avoid them..."
-Stephen Sibold, LLM, former Chair & CEO of the Canadian Securities Administrators
"...nethical insider trading is not a 'victimless crime'. Understanding that it is misappropriation that renders insider trading wrong makes it very clear who the victims of unethical insider trading are: they are the shareholders whose corporate information has been misappropriated...
...Although the primary victims of unethical insider trading are the shareholders of the company which is the subject of the inside information, they are not the only ones to suffer. If the insider trader is employed not by the subject company, but by a firm which was providing services to it, then that other firm and its shareholders will suffer as well. Because of the employee's fiduciary irresponsibility or theft, that organisation's reputation as a reliable adviser or agent, and consequently its ability to attract future customers, can be impaired..."
-Elaine Sternberg, PhD, Principal of Analytical Solutions
"...[T]here are those who argue that insider trading is a victimless offense and that enforcing insider trading prohibitions is simply not cost effective...
...But the options market presents a different story. Professional option writers write options only in response to a particular demand. Where that demand comes from an insider possessing material non-public information, the option writer suffers a loss that would not otherwise have occurred. Additionally, this penny-wise, pound-foolish argument neglects the external costs that result from a perception that insider trading is unchecked. In fact, as regulators throughout the world are discovering, governments cannot afford to turn a blind eye to insider trading if they hope to promote an active securities market and attract international investment..."
-Thomas Newkirk, LLB, former Associate Director, and Melissa A. Robertson,