The only time delivery company UPS contemplated breaching the Securities and Exchange Commission's safe-harbor rules on repurchasing company stock was the morning of the Sept. 11, 2001, terrorist attack on the World Trade Center.

Futures were down before the stock market opened that day, and Gary Barth, assistant treasurer and vice president at the Atlanta-based company, says he explained to his CFO that to support its stock price, UPS would face a market in which the only bids would be its own. That would almost certainly have resulted in UPS' falling outside the SEC's safe-harbor rules, which require that companies pay no more to repurchase stock than the highest independent bid or last independent sale price.

Scott Davis, UPS's CFO at the time and currently its CEO, gave the go-ahead. The issue was ultimately moot because the stock market never opened that day. However, UPS' predicament illustrates corporate America's reluctance to breach the safe-harbor restrictions, which include purchasing stock using no more than one broker-dealer per day; honoring limits near the market open and close; and purchasing no more than 25% of a stock's average daily trading volume.