Regulations
Futures markets are regulated by the federal Commodity Futures Trading Commission
(CFTC). The CFTC sets capital requirements for member firms of the futures exchanges,
authorizes trading in new contracts, and oversees maintenance of daily trading records.
The futures exchange may set limits on the amount by which futures prices may change
from one day to the next. For example, if the price limit on silver contracts is $1, and silver
futures close today at $16.10 per ounce, trades in silver tomorrow may vary only between
$15.10 and $17.10 per ounce. The exchange may increase or reduce these price limits in
response to perceived changes in the price volatility of the contract. Price limits often are
eliminated as contracts approach maturity, usually in the last month of trading.
Price limits traditionally are viewed as a means to limit violent price fluctuations.
This reasoning seems dubious, however. Suppose an international monetary crisis overnight drives up the spot price of silver to $25. No one would sell silver futures at prices
for future delivery as low as $16.10. Instead, the futures price would rise each day by
the $1 limit, although the quoted price would represent only an unfilled bid order—no
contracts would trade at the low quoted price. After several days of limit moves of $1 per
day, the futures price would finally reach its equilibrium level, and trading would resume.
This process means no one could unload a position until the price reached its equilibrium
level. This example shows that price limits offer no real protection against fluctuations in
equilibrium prices.
概括
期货市场由美国商品期货交易委员会（CFTC）监管，该机构负责设定交易所会员公司的资本要求、审批新合约交易并监督日常交易记录的维护。交易所可对期货价格的单日波动幅度设限，例如白银合约若当日收盘价为每盎司16.10美元且限幅为1美元，次日交易范围将限制在15.10至17.10美元之间。交易所会根据合约价格波动性调整限幅，临近交割月（通常为最后交易月）时往往取消限制。
价格限制传统上被视为抑制剧烈波动的工具，但其有效性存疑。假设国际货币危机导致白银现货价一夜飙升至25美元，无人会以16.10美元的低价卖出期货合约。此时期货价格虽会每日按1美元上限递增，但报价仅为未成交的买单，实际交易停滞，直至多日后达到均衡价格才恢复流动。这表明价格限制无法真正阻止均衡价格波动，反而可能延迟持仓者平仓时机。
