Option exercise limits, along with position limits (See KB1252), have been in place since the inception of standardized trading of U.S. securities options. Their purpose is to prevent manipulative actions in underlying securities (e.g., corners or squeezes) as well as disruptions in option markets where illiquidity in a given option class exists. These limits serve to prohibit an account, along with its related accounts, from cumulatively exercising within any five consecutive business day period, a number of options contracts in excess of the defined limit for a given equity options class (i.e., option contracts associated with a particular underlying security). This includes both early exercises and expiration exercises.
U.S. securities option exercise limits are established by FINRA and the U.S. options exchanges. The exercise limits are generally the same as position limits and they can vary by option class as they take into consideration factors such as the number of shares outstanding and trading volume of the underlying security. Limits are also subject to adjustment and therefore can vary over time. The Options Clearing Corporation (OCC), the central clearinghouse for U.S. exchange traded securities options, publishes a daily file with these limits on its public website. The link is as follows: http://www.optionsclearing.com/webapps/position-limits. FINRA Rule 2360(b)(4) addresses exercise limits and can be found via the following website link: http://finra.complinet.com/en/display/display.html?rbid=2403&record_id=16126&element_id=6306&highlight=2360#r16126).
Note that exercise limits are applied based upon the the side of the market represented by the option position. Accordingly, all exercises of call options over the past five business days are aggregated for purposes of determining the limit for the purposes of purchasing the underlying security. Similarly, a separate computation whereby all put exercises over the past five business days are aggregated is required for purposes of determining sales of the underlying.
It's important to note that while exercise limits may be set at levels identical to position limits, it is possible for an account holder to reach an exercise limit without violating positions limits for a given option class. This is because exercise limits are cumulative and one could conceivably purchase options up to the position limit, exercise those options and purchase additional options which, if allowed to be exercised within the five business day window, would exceed the limit.
Account holders are responsible for monitoring their cumulative options exercises as well as the exercise limit quantities to ensure compliance. In addition, IB reserves the right to prohibit the exercise of any options, regardless of their intrinsic value or remaining maturity, if the effect of that exercise would be to violate the exercise limit rule.