Financial Analysis: Do asset managers typically adjust earnings (for one-time losses or gains) figures before making an investment?

Depends. If the one-time loss has profound implications for the future business, they won't. Example:  BP oil spill in 2010, where they were possibly liable for spending billions of dollars helping cleaning up the mess. It created some serious doubts about their entire NA business, so the stock experienced incredible amount of volatility. The Gulf oil spill is recognized as the worst oil spill in U.S. history. Within days of the April 20, 2010 explosion and sinking of the Deepwater Horizon oil rig in the Gulf of Mexico that killed 11 people, underwater cameras revealed the BP pipe was leaking oil and gas on the ocean floor about 42 miles off the coast of Louisiana. By the time the well was capped on July 15, 2010 (http://ocean.si.edu/blog/gulfspillflashback-giving-gulf-oil-spill-consideration-it-deserves), an estimated 3.19 million barrels of oil had leaked into the Gulf.The well was located over 5,000 feet beneath the water’s surface in the vast frontier of the http://ocean.si.edu/deep-sea—a permanently dark environment, marked by constantly cold temperatures just above freezing and extremely high pressures. Scientists http://ocean.si.edu/ocean-photos/zones-open-ocean, and the deep ocean accounts for about three-quarters of Earth’s total ocean volume. But yes, in many cases, for small adjustments or irrelevant adjustments (like winning some trivial lawsuit), investors will discount that.