24/7 Wall St.

Stocks were indicated to open marginally higher on Tuesday morning after a larger sell-off on Monday. Investors have been having less success buying the stock market dips in 2018 than in prior years. Many investors also are reconsidering how they want their investments positioned ahead of the midterm elections and during international trade concerns.

24/7 Wall St. reviews dozens of analyst research reports each day of the week to find new investing and trading ideas for our readers. Some analyst reports cover stocks to buy, and some cover stocks to sell or to avoid.

Additional commentary has been added on most of the daily analyst reports, along with trading history. The consensus analyst price targets and other valuation metrics are from the Thomson Reuters sell-side research service.

These were the top analyst upgrades, downgrades and other research calls from Tuesday, July 31, 2018.

Athenahealth Inc. (NASDAQ: ATHN) was maintained as Hold but the price target was raised to $160 from $125 at Canaccord Genuity. Also, Stifel reiterated it as Hold and raised the price target to $140 from $134.

BioMarin Pharmaceutical Inc. (NASDAQ: BMRN) was reiterated as Buy and the price target was raised to $113 from $105 at Canaccord Genuity. Shares closed down 0.6% at $99.38 on Monday, in a 52-week trading range of $75.81 to $104.46.

Illumina Inc. (NASDAQ: ILMN) was reiterated as Buy and the price target was raised to $340 from $330. Deutsche Bank also reiterated its Buy rating and raised its target to $330 from $280.

Northrop Grumman Corp. (NYSE: NOC) was raised to Buy from Neutral and the price target was raised to $371 from $246 at Buckingham Research.

Nutrisystem Inc. (NASDAQ: NTRI) was downgraded to Neutral from Buy and the price target was lowered to $40 from $45 at D.A. Davidson. The stock closed down 2% on Monday at $38.50, but the shares were down 3.9% at $37.00 early Tuesday.

Signet Jewelers Ltd. (NYSE: SIG) was downgraded to Neutral from Buy at Nomura.

Square Inc. (NYSE: SQ) was maintained as Buy and the price target was raised to $72 from $66 at Stifel.

TJX Companies Inc. (NYSE: TJX) was reiterated as Buy and the target price was raised to $111 from $96 at Citigroup.

Twitter Inc. (NYSE: TWTR) was raised to Neutral from Reduce at Nomura. Twitter was hit hard on earnings last week and closed down 8% at $31.38 on Monday. Its shares were last seen up 1.2% at $31.75 on Tuesday.

Yamana Gold Inc. (NYSE: AUY) was raised to Outperform from Market Perform and the price target was raised to $4.25 from $3.00 (versus a $3.10 prior close) at BMO Capital Markets. The 52-week range is $2.40 to $3.80.

Monday’s top analyst upgrades and downgrades were in Ally Financial, Amgen, AT&T, BP, Chesapeake Energy, Expedia, National Oilwell Varco, Square, Synchrony, Twitter and many more.

Follow @Jonogg on Twitter to receive the daily analyst calls and other market research calls directly on your feed.