Answer:
seven days.
Step-by-step explanation:
Securities and Exchange Commission Form X-17A-5 Part II specifically states that brokers or dealers must deduct any differences resulting from aged short securities:
"Deduct the market value of all short securities differences unresolved for 7 business days after discovery and the market value of any long security differences where such securities have been sold by the broker or dealer until they are adequately resolved, less any reserves established therefor."