Established on June 12, 1946 under SEC Registration No. 1675. It was fully owned by UNACO. MASCO was part of the Underwriters Adjustment Company (UNACO) in the Far East which includes KASCO, MALACO, GIA, SASCO, BACO (THAILAND) AND AIC (TAIWAN).
MASCO changed its corporate name on March 5, 1974 from MACO, Manila Adjustment Company to Manila Adjusters & Surveyors Company.
On June 14, 1974 MASCO was restructured to give way to the increase of Filipino equity participation to 60% and reducing the foreign capitalization to 40%. On July 1, 1974 at the expiry of the Laurel Langley Agreement a Filipino president assumed office.
On June 12, 1996, the corporate life of MASCO was extended to another 50 years.
On August 12, 2016, MASCO became a fully and Filipino company with First Choice Multiline Corp. as its major stock holder.