Keshk, Walied; Lu, HungYuan Richard; Mande, Vivek (2020). How have US banks adopted the Financial Accounting Standards Board's Level 3 fair value disclosure rules? Accounting & Finance 60, April Supplement S1, 693-727.

Explain the difference between Levels 1, 2, and 3. Keshk et al (2020) categorize levels 1,2 together, so you are free to do so but are not required. You may cite and reference other sources to answer this question.

. If you were an auditor, which type of estimate requires more work to audit Levels 1,2 or Level 3? Explain.