Take a look at some of the biggest movers in the premarket:

Carvana (CVNA) – Carvana was downgraded to “sector perform” from “outperform” at RBC Capital Markets, with the price target for the online car seller’s stock cut to $138 per share from $155 per share. RBC bases its call both on valuation and potential difficulty in integrating its recent acquisition of car auction company Adesa. Carvana slid 3.4% in the premarket.

First Solar (FSLR) – The solar company’s stock fell 4.8% in premarket trading after Bank of America Securities downgraded it to “underperform” from “neutral.” BofA said investors may be overly optimistic about growth prospects and that a new Commerce Department anti-dumping inquiry into Asian module manufacturers is unlikely to drive pricing power.

Generac (GNRC) – The maker of backup generators and other energy-related equipment was put on the “Americas Buy List” at Goldman Sachs. Goldman points to a broad product portfolio, an increasing distribution footprint, and the idea that many of Generac’s products are in the early stages of adoption. Generac added 2.1% in premarket trading.

Carnival (CCL) – Carnival rallied 3.6% in the premarket after the cruise line operator said the seven-day period from March 28 through April 3 was the busiest week for new cruise bookings in the company’s history.

Twitter (TWTR) – Twitter was up another 1.5% in premarket action after soaring 27.1% Monday. That followed Tesla CEO Elon Musk’s disclosure that he had taken a 9.2% stake in the social media company.

Nio (NIO) – Nio gained 1.1% in the premarket following a report in the Financial Times that the China-based electric car maker is speaking with peers about licensing its battery swapping technology.

Farfetch (FTCH) – The luxury fashion e-commerce company will take a $200 million minority stake in Neiman Marcus as part of a global partnership.

Acuity Brands (AYI) – The maker of lighting products and building management systems reported quarterly earnings of $2.57 per share, 20 cents a share above estimates. Revenue also topped Wall Street forecasts. The company said it was able to offset significant increases in materials and freight costs with price increases and productivity improvements.

Teva Pharmaceutical (TEVA) – The drugmaker was upgraded to “overweight” from “equal weight” at Barclays, which cited several factors including increased estimates for Teva’s biosimilar version of the immunosuppressive drug Humira. Teva added 1.5% in premarket trading.