Olympus had made signicant investments in the late 19803 that lost substantial value in the 1990s. Since Japanese GAAP allowed these investments to be valued at cost, Olympus was able to hide unrealized losses by not selling these investments. Under US. GAAP, investments in marketable securities have been reported at fair value since the adoption of SFAS No. 115 in 1993. a. Discuss the pros and cons of valuing investments at cost versus fair value from the perspective of decision-usefulness in nancial reporting