Catch up on today's top five analyst downgrades with this list compiled by The Fly: 1. Twitter (TWTR) downgraded to Underperform from In Line at Evercore ISI with analyst Kevin Rippey citing his view that 2018 represented a period of "unsustainably high" margins as Twitter reaped the benefits of a period of sustained underinvestment. 2. Mylan (MYL) downgraded to Equal Weight from Overweight at Morgan Stanley with analyst David Risinger sayinge has become more conservative in his estimates after competing U.S. generic businesses missed estimates in the past two days, which he thinks may be indicative of ongoing industry pressures. 3. Expedia (EXPE) downgraded to Neutral from Overweight at Piper Jaffray and to Neutral from Buy at DA Davidson and BofA/Merrill. 4. Bloomin' Brands (BLMN) downgraded to Neutral from Overweight at JPMorgan with analyst John Ivankoe citing valuation. 5. Papa John's (PZZA) downgraded to Neutral from Buy at MKM Partners with analyst Brett Levy saying the company has generated its first positive domestic comps in two years while laying the foundation for a "potential turnaround," but after a 43% run-up in the stock price since August 23, he believes the valuation warrants a neutral stance. This list is just a portion of The Fly's full analyst coverage. To see The Fly's full Street Research coverage, click here.