Stocks making the biggest moves premarket: Micron, Broadcom, Wynn Resorts, Carnival & more

Check out the companies making headlines in the premarket Monday:

Micron Technology, Skyworks Solutions, Broadcom — Chipmaker shares rose broadly after President Donald Trump and Chinese President Xi Jinping agreed the U.S. and China will not impose additional tariffs on each other's goods. Micron and Skyworks both jumped more than 6% in the premarket, while Qualcomm gained 5.5%.

Wynn Resorts, Las Vegas Sands — Casino stocks climbed in the premarket after the Macau gaming authority reported gambling revenues rose more than expected in June. Gross gaming revenue in Macau rose 5.9% last month, well above a StreetAccount estimate of 2.5% growth. Wynn and Las Vegas Sands rallied more than 4% each before the bell.

Carnival — The cruise operator was downgraded to "hold" from "buy" at Berenberg. The firm also slashed its price target on Carnival to $48 per share from $60 a share. Berenberg cited expectations of slow growth through 2020 for the downgrade. Carnival shares slid 0.3%.

KB Home — KB Home shares were upgraded to "neutral" from "sell" by an analyst at BTIG. The analyst cited better-than-expected quarterly results, but "the biggest positive surprise is a greater proportion of CA orders and backlog that will help offset weaker margins in other markets in late 2019 and likely early 2020."

Evo Payments — BTIG downgraded the payments company to "neutral" from "buy," citing a "full" valuation after the stock's 27% surge this year. The firm added: "We continue to believe the company … is well positioned to achieve low double-digit to mid-teens revenue growth and expanding margins while generating strong free cash flow and de-leveraging at a healthy clip."

United Therapeutics — An analyst at Credit Suisse upgraded United Therapeutics to "outperform" from "neutral." The analyst, who also raised his price target on the stock to $101 per share from $98 a share, said United Therapeutics valuation is attractive at current levels.

Biogen — Biogen shares gained 0.9% in the premarket after the company reported positive results for its spinal muscular atrophy drug, Spinraza. The company said pre-symptomatic infants who were treated with the drug achieved "unprecedented" milestones, including 88% of children walking independently.

Berkshire Hathaway — Berkshire Hathaway Chairman and CEO Warren Buffett has pledged to donate $3.6 billion worth of Berkshire stock across five different charities, the company said in a release Monday.