Better to subdivide 4000 sq ft parcel of land or sell as whole in a down market

or should I wait until prices start moving up.

You can actually go experiment on either. Try researching on what will be the individuals values and ROI if you try to subdivide the properties. Will it make sense and will you not lost too much of the probably profit? What if you sell it as a whole in a down market? or waited until the market picks up? There are many things to consider first. And it depends on you and how you weigh such things.