Catch up on today's top five analyst upgrades with this list compiled by The Fly: 1. HD Supply (HDS) upgraded to Buy from Hold at SunTrust with analyst Keith Hughes saying the current valuation on the stock is too low at 10.7-times enterprise value to EBITDA, with his new price target taking that valuation to the upper middle of the distribution group range. 2. Viacom (VIAB) upgraded to Buy from Hold at Needham with analyst Laura Martin saying the stock's forward PE valuation at 8.2-times is 15%-30% below peers mainly due to Paramount's losses. 3. Akamai (AKAM) upgraded to Sector Weight from Underweight at KeyBanc with analyst Brandon Nispel saying Akamai's ability to expand margins is greater than he anticipated and that fears surrounding growth are "unlikely to come to fruition near term." 4. Aon plc (AON) upgraded to Buy from Neutral at Goldman Sachs while Willis Towers Watson (WLTW) was upgraded to Neutral from Sell. 5. Exxon Mobil (XOM) upgraded to Buy from Reduce at HSBC. This list is just a portion of The Fly's full analyst coverage. To see The Fly's full Street Research coverage, click here.