## CMO Workflow

In general, the CMO workflow is:

Calculate underlying mortgage cash flows.

Define CMO tranches

If using a PAC or TAC CMO, calculate the principal schedule.

Calculate cash flows for each tranche.

Analyze the CMO by computing price, yield, spread of CMO cash flows.

### Calculate Underlying Mortgage Cash Flows

Underlying mortgage pool pass-through cash flows are calculated
by the existing function `mbspassthrough`

.
The CMO cash flow functions require the principal payments (including
prepayments) calculated from existing functions `mbspassthrough`

or `mbscfamounts`

.

principal = 10000000; coupon = 0.06; terms = 360; psa = 150; [principal_balance, monthly_payments, sched_principal_payments,... interest_payments, prepayments] = mbspassthrough(principal,... coupon, terms, terms, psa, []); principal_payments = sched_principal_payments.' + prepayments.';

After determining principal payments for the underlying mortgage
collateral, you can generate cash flows for a sequential CMO, with
or without a Z-bond, by using `cmoseqcf`

.
For a PAC or TAC CMO, the cash flows are generated using `cmoschedcf`

### Define CMO Tranches

Define CMO tranche; for example, define a CMO with two tranches:

TranchePrincipals = [500000; 500000]; TrancheCoupons = [0.06; 0.06];

### If Using a PAC or TAC CMO, Calculate Principal Schedule

Calculate the PAC/TAC principal balance schedule based on a band of PSA speeds. For scheduled
CMOs (PAC/TAC), the CMO cash flow functions additionally take in the principal
balance schedule calculated by the CMO schedule function `cmosched`

.

```
terms = 360;
coupon = 0.06;
principal = 10000000;
speed = [100 300];
[balanceSchedule, initialBalance] = cmosched(principal, coupon,...
terms, terms, speed, TranchePrincipals(1));
```

### Calculate Cash Flows for Each Tranche

You can reuse the output from the cash flow generation functions
to further divide the cash flows into tranches. For example, the output
from `cmoschedcf`

for a PAC tranche
can be divided into sequential tranches by passing the principal cash
flows of the PAC tranche into the `cmoschedcf`

function.
The outputs of the CMO cash flow functions are the principal and
interest cash flows, and the principal balance.

```
[principal_balances, principal_cashflows, interest_cashflows] = cmoschedcf(principal_payments,...
TranchePrincipals, TrancheCoupons, balanceSchedule);
```

### Analyze CMO by Computing Price, Yield, and Spread of CMO Cash Flows

The outputs from the CMO functions (`cmoseqcf`

and `cmoschedcf`

) are cash flows. The functions
used to analyze a CMO are based on these cash flows. To that end,
you can use `cfbyzero`

, `cfspread`

, `cfyield`

,
and `cfprice`

to compute prices,
yield, and spreads for the CMO cash flows. In addition, using the
following, you can calculate a weighted average life (WAL) for each
tranche in the CMO:

$$WAL={\displaystyle \sum _{i=1}^{n}\frac{{P}_{i}}{P}}{t}_{i}$$

where:

*P* is the total principal.

*P _{i}* is the principal
repayment of the coupon

*i*.

$$\frac{{P}_{i}}{P}$$ is the fraction of the principal
repaid in coupon *i*.

*t _{i}* is the time in
years from the start to coupon

*i*.

## See Also

`cmoseqcf`

| `cmosched`

| `cmoschedcf`

| `mbscfamounts`

| `mbspassthrough`

## Related Examples

- Using Collateralized Mortgage Obligations (CMOs)
- Create PAC and Sequential CMO
- Fixed-Rate Mortgage Pool