Explain why we need to bother about modeling the joint distribution of N risk factors. Given the

Question:

Explain why we need to bother about modeling the joint of N risk factors. Given the problems created by the dimensionality that increases with the square of N, it would seem simpler to apply univariate GARCH to the current only.
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most... Portfolio
A portfolio is a grouping of financial assets such as stocks, bonds, commodities, currencies and cash equivalents, as well as their fund counterparts, including mutual, exchange-traded and closed funds. A portfolio can also consist of non-publicly...