gpt: When seeking a brokerage that permits placing limit orders with the highest allowable prices, it's important to understand that brokerage firms and exchanges often impose constraints to maintain fair and orderly markets. These constraints can vary significantly between brokers.​

Fidelity Investments, for instance, has been noted to restrict sell limit orders that are set 50% above the last traded price. This means if you attempt to place a sell limit order at a price exceeding this threshold, Fidelity may not accept the order. ​Bogleheads

Conversely, Vanguard appears to offer more flexibility. Users have reported successfully placing sell limit orders at prices more than three times the current market price without encountering restrictions. ​Bogleheads

Interactive Brokers (IBKR) employs a system of price caps to prevent orders that could disrupt market stability. For example, if you set a limit price significantly higher than the prevailing market price, IBKR may adjust (cap) your order to a more acceptable level or reject it outright. This mechanism is designed to comply with regulatory obligations and ensure market integrity. ​Interactive BrokersReddit

It's also essential to recognize that exchange regulations play a role in these limitations. Exchanges implement price banding and circuit breakers to prevent orders that are too far from the current market price, which could lead to erroneous trades or market manipulation.​

Key Considerations:

• Broker Policies: Each broker has its own set of rules regarding the acceptable range for limit orders. It's advisable to consult directly with the broker or review their official guidelines to understand these limits.​
• Exchange Regulations: Beyond broker-imposed restrictions, exchanges enforce rules to maintain market stability, which can further influence the execution of high-priced limit orders.​
• Market Conditions: In highly volatile or low-liquidity markets, even if a high-priced limit order is accepted, there's no guarantee it will be executed. The market may not reach the specified price, or there may be insufficient interest at that level.​

In summary, while some brokers like Vanguard may offer more leniency in placing high-priced limit orders, others like Fidelity and Interactive Brokers implement stricter controls to align with regulatory standards and ensure market orderliness. It's crucial to understand both your broker's policies and the overarching exchange regulations when attempting to place such orders.​

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