Stocks were indicated to open higher yet again on Monday, with the Dow and S&P 500 challenging all-time highs. The bull market is now well over eight years old, but the one theme that persists is that investors keep finding new reasons to buy the major indexes and their favorite stocks after each and every single sell-off. Investors are also searching for new investing and trading ideas.

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 color and commentary has been added on most of the daily analyst calls. Consensus analyst price target data are from the Thomson Reuters sell-side research service.

These were the top analyst upgrades, downgrades and other research calls from Monday, July 31, 2017.

American Airlines Group Inc. (NASDAQ: AAL) was raised to Outperform from Market Perform with a $57 price target (versus a $50.49 prior close) at Cowen. American Airlines was indicated up 1.2% at $51.10, and it has a 52-week trading range of $33.00 to $54.48. Its consensus analyst target price is $58.06.

Celgene Corp. (NASDAQ: CELG) was raised to Buy from Hold with target of $160 at Argus. The upgrade reflects the strong second-quarter sales of Pomalyst and Otezla, which are providing Celgene with additional growth drivers and reducing its reliance on Revlimid. The firm also expects new indications for Pomalyst, Otezla and for Revlimid, which could all be additional revenue and growth drivers. The stock has a 52-week range of $96.93 to $139.00 and consensus target price of $146.55.

Citigroup Inc. (NYSE: C) was downgraded to Market Perform from Outperform with a $65 price target (versus a $67.43 close) at BMO Capital Markets. Citigroup was actually indicated higher by 0.6% with the markets up on Monday, and the call was signaling a valuation call. Another supporting call for Citi was Barron’s, noting over the weekend that Citi shares might be able to rise another 50%. Citigroup has a 52-week range of $42.50 to $68.91 and a consensus price target of $71.62.

Facebook Inc. (NASDAQ: FB) was downgraded to Sell from Hold with a $140 price target (versus a $172.45 close) at Pivotal Research. Facebook has a 52-week range of $113.55 to $175.49 and a consensus price target of $187.59, but many analysts have been raising their targets in a much different view than this call from Pivotal.

Hertz Global Holdings Inc. (NYSE: HTZ) was downgraded to Underweight from Equal Weight with a $9 price target (versus a $17.34 close) at Barclays. Hertz was down 6% at $16.30 on Monday, in a 52-week range of $8.52 to $52.27. The prior consensus target price was $17.00.

Hilton Worldwide Holdings Inc. (NYSE: HLT) was raised to Hold from Sell with a $65 price target (versus a $62.46 close) at Berenberg. Hilton has a 52-week range of $44.73 to $67.79 and a consensus price target of $69.10.

ULTA Beauty Inc. (NASDAQ: ULTA) was downgraded to Perform from Outperform with a $270 price target (versus a $248.60 close) at Oppenheimer. Ulta has a 52-week range of $225.13 to $314.86 and a consensus analyst target of $324.45.

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Other key analyst upgrades, downgrades and initiations were seen as follows: