Catch up on today's top five analyst upgrades with this list compiled by The Fly: 1. Costco (COST) upgraded to Overweight from Equal Weight at Barclays with analyst Karen Short citing a survey by the firm where results showed analytically that Costco (COST) is "very protected" from Amazon (AMZN). 2. CSX (CSX) was upgraded to Buy from Hold at Aegis and to Outperform from Market Perform at Raymond James. 3. Gigamon (GIMO) upgraded to Buy from Hold at Stifel with analyst Patrick Newton citing valuation and his belief that the company has a number of potential positive catalysts, including the 100G upgrade cycle at T-Mobile (TMUS), in-line SSL decryption, and the potential for reduced competition from Ixia (XXIA). 4. Skechers (SKX) upgraded to Buy from Neutral at B. Riley with analyst Jeff Van Sinderen citing "strong" international growth and worldwide comps following the company's better than expected first quarter results. The analyst raised his price target for the shares to $32 from $28. 5. Quest Diagnostics (DGX) upgraded to Outperform from Market Perform at Raymond James with analyst Nicholas Jansen saying Quest has delivered two strait quarters of high single digit adjustment EBIT growth and sees room for sustained mid-to-high single digit growth driven by improved commercial execution, strengthening health system relationships and outreach deals, and invigorate programs. This list is just a portion of The Fly's full analyst coverage. To see The Fly's full Street Research coverage,
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