Stock trading limit order coupled link (LOCK)

A computer of a host securities broker that is configured to communicate with a securities exchange, comprising:

• a computer that is configured for receiving over the Internet at the host securities broker a customer order to trade a security, the customer order comprising a first condition that specifies when to execute a first order for trading the security, and a second condition that specifies when to execute a second order for trading the security after the first condition has been satisfied, tracking at the host securities broker a current market price of the security, for determining at the host securities broker whether the first condition has been satisfied, for transmitting from the host securities broker the first order for execution at the securities exchange when the current market price of the security satisfies the first condition, for receiving at the host securities broker a confirmation of the execution of the first order, for determining at the host securities broker whether the second condition has been satisfied, and for transmitting from the host securities broker the second order for execution at the securities exchange when the current market price satisfies the second condition.

A system that is configured to communicate with a securities exchange, comprising:

• a plurality of servers controlled by a host securities broker, wherein the plurality of servers are configured for receiving over the Internet at the host securities broker a customer order to trade a security, the customer order comprising a first condition that specifies when to execute a first order for trading the security, and a second condition that specifies when to execute a second order for trading the security after the first condition has been satisfied, tracking at the host securities broker a current market price of the security, for determining at the host securities broker whether the first condition has been satisfied, for transmitting from the host securities broker the first order for execution at the securities exchange when the current market price of the security satisfies the first condition, for receiving at the host securities broker a confirmation of the execution of the first order, for determining at the host securities broker whether the second condition has been satisfied, and for transmitting from the host securities broker the second order for execution at the securities exchange when the current market price satisfies the second condition.