Complex sentence: The SPAC must sign a letter of intent for a merger or an acquisition within 18 months of the IPO or it will be forced to dissolve and return the assets in the trust to public stockholders.
Split into simpler sentences: The SPAC must sign a letter of intent for a merger or an acquisition within 12-18 months of the IPO. Otherwise it will be forced to dissolve and return the assets held in the trust to the public stockholders.