1. A computer-implemented method of allocating a trade of a number of financial instruments, the method comprising: receiving at an allocation management system from an order management systems a message descriptive of a trade of a financial instrument, the message comprising a financial instrument identifier and a size of the trade; determining a risk class associated with the identified financial instrument; determining a first plurality of portfolios associated with the risk class and a target ratio for each of the portfolios; and allocating the trade of the financial instrument among each of the first plurality of portfolios based on the target ratio associated with each of said portfolios.