A computer implemented method for cross asset correlation and margining in a trading system, comprising: receiving, by a processor, portfolio data for a plurality of portfolios; calculating a first plurality of simulations for the each of the plurality of portfolios; determining, by the processor, a single portfolio performance vector for each of the plurality of portfolios based on a portfolio specific model and results of the first plurality of simulations; calculating a second plurality of simulations for the each of the plurality of portfolios; determining, by the processor, a joint portfolio performance vector for the plurality of portfolios based on portfolio specific models and results of the second plurality of simulations; determining, by the processor, for each portfolio, a portfolio specific scalar based on the single portfolio performance vector and the joint portfolio performance vector; and modifying, by the processor, a portfolio risk based on the portfolio specific model and the portfolio specific scalar, generating and transmitting, by the processor, a plurality of messages for an initial margin for the plurality of portfolios based on the modified portfolio risk, wherein the number of the plurality of messages for the trading system is reduced for margin requirements due to the portfolio specific model and portfolio specific scalar, wherein as asset class margin (Λ k) for an asset class (Λ k) is calculated according to: Λ k = Percentile Θ P & L, wherein Percentile is a function that returns a margin value for the asset class margin (Λ k) according to a probability distribution for a profit and loss derived from the first plurality of simulations, wherein the joint margin (Λ joint) is calculated according to: Λ joint = Percentile Θ P & L, wherein Percentile is a function that returns a margin value for the joint asset margin (Λ joint) according to a probability distribution for the profit and loss (P&L) derived from the second plurality of simulations, wherein a reduced initial margin is calculated according to: IM = Λ k − w k ⋅ Λ joint wherein the asset class margin (Λ k) is reduced by a contribution w k portion of the joint asset margin (Λ joint), receiving, by a processor, portfolio data for a plurality of portfolios; calculating a first plurality of simulations for the each of the plurality of portfolios; determining, by the processor, a single portfolio performance vector for each of the plurality of portfolios based on a portfolio specific model and results of the first plurality of simulations; calculating a second plurality of simulations for the each of the plurality of portfolios; determining, by the processor, a joint portfolio performance vector for the plurality of portfolios based on portfolio specific models and results of the second plurality of simulations; determining, by the processor, for each portfolio, a portfolio specific scalar based on the single portfolio performance vector and the joint portfolio performance vector; and modifying, by the processor, a portfolio risk based on the portfolio specific model and the portfolio specific scalar, generating and transmitting, by the processor, a plurality of messages for an initial margin for the plurality of portfolios based on the modified portfolio risk, wherein the number of the plurality of messages for the trading system is reduced for margin requirements due to the portfolio specific model and portfolio specific scalar, wherein as asset class margin (Λ k) for an asset class (Λ k) is calculated according to: Λ k = Percentile Θ P & L, wherein Percentile is a function that returns a margin value for the asset class margin (Λ k) according to a probability distribution for a profit and loss derived from the first plurality of simulations, wherein the joint margin (Λ joint) is calculated according to: Λ joint = Percentile Θ P & L, wherein Percentile is a function that returns a margin value for the joint asset margin (Λ joint) according to a probability distribution for the profit and loss (P&L) derived from the second plurality of simulations, wherein a reduced initial margin is calculated according to: IM = Λ k − w k ⋅ Λ joint wherein the asset class margin (Λ k) is reduced by a contribution w k portion of the joint asset margin (Λ joint),