Which of the following is a condition for HSR filing, even if the transaction is smaller than the minimum value?

The correct choice reflects a condition that can trigger HSR filing, even when the transaction size falls below the typical minimum thresholds. Specifically, the requirement for substantial sales by all parties in the previous fiscal year can warrant an HSR filing. This condition applies as a means to ensure that transactions which might not meet the size threshold nevertheless involve significant financial entities that could affect market competition.

The rationale for this requirement lies in the intent of the Hart-Scott-Rodino Antitrust Improvements Act (HSR Act) to prevent anticompetitive practices, even in smaller transactions. It underscores the importance of the parties' market presence and activities, which can have implications for competition regardless of the dollar amount involved in the transaction.

The other options do not adequately reflect the conditions set forth under the HSR Act for transactions that may still require a filing despite being below the dollar threshold.