Citadel Securities generated a record $7.3 billion in trading revenue during the second quarter, more than triple its result from the same period last year and well above the $4.3 billion reported for the first quarter. The firm’s strongest quarter on record was driven by surging retail activity and all-time highs in U.S. equity and options trading volumes. Net income rose more than 250% to $3.3 billion, while the firm expanded its high-touch equities business and moved into investment-grade corporate bond trading. The results highlight the growing scale of nonbank market makers, including Hudson River Trading and Jane Street Group, and may intensify debate over market structure, payment for order flow and whether retail investors receive the best execution.