* In an $N$ state Markov state version, $N$ such securities are traded each period.

* In a continuous state Markov state version, a continuum of such securities are traded each period.

These state-contingent securities are commonly called Arrow securities, after Kenneth Arrow <https://en.wikipedia.org/wiki/Kenneth_Arrow>

These state-contingent securities are commonly called Arrow securities, after [Kenneth Arrow](https://en.wikipedia.org/wiki/Kenneth_Arrow).

In the **incomplete markets version**, the consumer can buy and sell only one security each period, a risk-free one-period bond with gross

one-period return $\beta^{-1}$.