Financial markets enable price discovery. Price information and price discovery are generally considered to be good for the public. As most AT systems make use of limit orders, they provide liquidity to financial markets. Limit orders add information to the market. AT systems add to price information and, therefore, price discovery. Several academic studies show that AT increases liquidity and decreases volatility. Thus, this activity cannot be construed as inherently unethical.
Rather than the ethics of AT, AT 9000 consider ethics in AT. By ethics we mean those standards of conduct that apply to AT firms, and the primary ethical component is responsibility.