Institutional investors and professional traders rely on The Fly to learn which companies the best analysts on Wall Street are saying to buy and sell.

Research analysts at Wall Street's largest banks issue recommendations on whether a stock should be bought, held, or sold. The Fly's team of financial market experts scours hundreds of research notes daily to uncover the best trading ideas. Check out today's top analyst calls from around Wall Street, compiled by The Fly.

Top 5 Upgrades:

• Piper Sandler analyst Michael Lavery upgraded Kellogg (K) to Neutral from Underweight with a price target of $74, up from $64. The analyst states that he had been cautious on the stock as consumers have indicated that they trade down on cereal consumption due to inflation headwinds, but his sum-of-the-parts analysis after Kellogg announced a split into three entities suggests that the shares are now "fairly valued."
• BofA analyst Jason Gerberry upgraded Teva (TEVA) to Buy from Neutral with a price target of $13, up from $10. The company is making material progress toward cleaning up its litigation overhangs and finalizing opioid settlements, which should be enough to shift Teva back to EBITDA growth, the analyst tells investors in a research note.
• Stifel analyst Patrick Ho upgraded Advanced Energy (AEIS) to Buy from Hold with a price target of $110, up from $94, following the company's recent earnings release and its positive outlook for the next few quarters. Advanced Energy has addressed two of his major concerns recently, as on the semis end he is encouraged over the improvements on the operations and on the Artesyn end he believes management has refocused its strategic vision and redeployed resources appropriately, Ho tells investors.
• Piper Sandler analyst Paul Newsome upgraded United Fire Group (UFCS) to Overweight from Neutral with an unchanged price target of $37. The analyst believes better than expected underwriting results is offsetting higher expense increases.
• Stifel analyst Jim Duffy upgraded Fox Factory (FOXF) to Buy from Hold with a price target of $115, up from $88. The company's Q2 results and the outlook "frame beat and raise opportunity into 2023," Duffy tells investors in a research note.
  
  

Top 5 Downgrades:

• Susquehanna analyst Shyam Patil downgraded Twitter (TWTR)  to Neutral from Positive with a $45 price target, down from $50. The analyst cites the "associated uncertainty and disruption" related to the pending takeover by Tesla (TSLA) CEO Elon Musk for the downgrade.
  
• Credit Suisse analyst Nicholas Campanella downgraded Duke Energy (DUK) to Neutral from Outperform with a price target of $114, up from $112. Following the company's Q2 earnings report, the analyst sees see increased risk of a "re-base" to its 5%-7% long-term annual earnings growth target.
• JPMorgan analyst Bill Peterson double downgraded Hyzon Motors (HYZN) to Underweight from Overweight without a price target. Yesterday's filing after market close indicates a "material financial control issue within the company," Peterson tells investors in a research note. Wedbush analyst Daniel Ives also downgraded Hyzon Motors to Neutral from Outperform with a $3 price target.
• Stifel analyst J. Parker Lane downgraded Twilio (TWLO) to Hold from Buy with a price target of $90, down from $200. While total revenue and non-GAAP operating margin beat during the quarter, the company offered an outlook for Q3 that came in below consensus on the top and bottom-lines, Lane tells investors in a research note.
• Oppenheimer analyst Justin Kim downgraded BioCryst (BCRX) to Perform from Outperform without a price target following the Q2 financial results. With the execution on Orladeyo's commercial coming as anticipated, the notable updates for the shares had been the lifting of the FDA's partial clinical hold and broader M&A activity in the space, and Kim believes current levels may fairly price the shares.
  
  

Top 5 Initiations:

• Barclays analyst Christine Cho initiated coverage of Sunnova Energy (NOVA) with an Overweight rating and $35 price target. The analyst initiated coverage of the North America clean technology space with a Positive view. Within residential solar, Cho sees installers Sunnova Energy and Sunrun (RUN) as best positioned.
  
• Morgan Stanley analyst Mark Purcell resumed coverage of GSK plc (GSK) with an Equal Weight rating and 1,860 GBp price target. The analyst expects growth in older adult vaccines and a shift to specialist medicines to drive "above-consensus earnings momentum" for the company.
• Goldman Sachs analyst Marcio Farid initiated coverage of Southern Copper (SCCO) with a Neutral rating and $65 price target. The company's advantageous cost-curve position and sizable exposure to copper put Southern Copper in a strategic position to capture the copper scarcity that Goldman Sachs commodities team forecasts for the next few years, the analyst tells investors in a research note.
• JPMorgan analyst Philip Cusick reinstated coverage of Lumen Technologies (LUMN) with an Underweight rating and $10 price target following a period of restriction. With the sales of its Latin America and ILEC assets, Lumen has reduced the size and complexity of the company as well as reduced the number of markets that need to be upgraded, Cusick tells investors in a research note.
• Lake Street analyst Kyle Bauser initiated coverage of Electromed (ELMD) with a Buy rating and $20 price target. Electromed develops and sells an airway clearance therapy called SmartVest for patients with compromised pulmonary function and is "the last device pure-play in the bronchiectasis market," said Bauser.