“mortgage current coupon rate”
Not at all clear
who pays the interest? Who gets the interest?
And to further clarify — the Mortgage RATE is the coupon on the home mortgage, 4%, 3%, etc... I borrow $300k for a home, they charge me that every year on the balance. The homeowner PAYS interest.
That mortgage and hundreds of others are put into a pool and fractionalized into bonds secured by the mortgages, becoming Mortgage Backed Securities that can be traded like a stock. When you buy a MBS, you are (usually) wanting to get paid more than you invested. The investor RECEIVES interest.