You can apply for a reentry permit (on form I-131) before you leave the US. You can depart before the reentry permit is approved.
With such a reentry permit, you can return to the U.S. even after one year until the reentry permit’s expiration date. Reentry permits are issued for two years. You cannot renew a reentry permit, but you can return to the U.S. for a short time and apply for a new one. The second such reentry permit will be granted for two years ago, but subsequent ones may only be approved for one year at a time. An investor should consult with an immigration attorney.