underwrite

To assume financial responsibility for; agree to pay the costs of.

To supply with funding, especially as a sponsor.

To sign (an insurance policy) so as to assume liability in case of specified losses.

To insure.

To insure against losses totaling (a given amount).

To guarantee the purchase of (a full issue of stocks or bonds).

To agree to buy the unsold part of (stock not yet sold publicly) at a fixed time and price.