MMULT with non-adjacent / discontinuous columns

Hi,

I am struggling with a MMULT formula I need to make dynamic.

My data consists of a table with asset allocations for 4 different products, and a table with an investor's proportion of each product.

Normally, the MMULT function would work just fine, given that the investor had invested in all 4 products because both arrays would then be adjacent.

However, in my example that is not the case. The investor might invest in any number of portfolio (in the attached example he does not invest in Product 2), and the order in which the products appear in his portfolio might not always be A-Z (in the sample, it could e.g. be: Product 4 25%, Product 1 25%, Product 3 50%).

Is there a way to base the MMULT function on the entire asset allocation table (i.e. C4:F13), create a subarray consisting of only the allocations of the products actually invested in (i.e. those products mentioned in C16:E16)?

Thanks.