????債務上限的千年蟲危機

????據很多交易員稱，華爾街的計算機系統通過自動程序將美國政府的利息支付轉給債券持有人。甚至可能在這些資金尚未到賬的情況下。不同于其他債券，這些計算機沒有設計程序先檢查支付資金，因為每個人都假定美國政府會按時付款。這下糟了。

????如果美國政府停止支付，大銀行可能得拿出自己的現金來支付這些并不屬于它們的債務的利息。這可能造成一些交易商遠離美國國債市場，讓美國國債交易更為困難。或者，它可能占據銀行體系資金，導致銀行難以進行借貸和交易。

????另外一個問題：交易員利用美國國債為衍生品和其他交易提供融資。通常情況下，美國國債的利息可以覆蓋這些交易相當一部分的持有成本。支付轉移也被設置為自動完成。因此，美國政府違約可能導致其他很多交易員自動違約，觸發可能造成各個市場暴跌的拋盤浪潮。結果將是一片混亂。

????Debt ceiling's Y2K-like problem

????According to a number of traders, Wall Street's computer systems are programmed to automatically pass along U.S. government payments to bond holders. Even, perhaps, if those payments aren't made. Unlike other bonds, the computers aren't coded to check for the payments first, because everyone assumed Uncle Sam would always pay on time. Oops.

????If the government stops making payments, big banks could be shelling out their own cash to pay interest on debt that's not theirs. That could cause some dealers to back away from the Treasury market, making it harder to trade U.S. debt. Or it could just be a drain on the banking system, making it difficult for banks to lend and trade.

????Another problem: Traders leverage Treasury bonds to finance derivative bets and other transactions. Often the interest on Treasuries covers much of the carrying cost of those trades. And the transfers of payments are set up to be automatic as well. So a government default could lead lots of other traders to automatically default, triggering a wave of selling that could cause a variety of markets to tumble. It would be a mess.