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

GenMark Diagnostics (GNMK) – GenMark will be bought by Swiss drugmaker Roche for $1.8 billion in cash, or $24.05 per share. Shares of the U.S.-based molecular diagnostic test maker had closed at $18.50 per share on Friday. GenMark surged 29.2% in premarket action.

NXP Semiconductors (NXPI), Penn National Gaming (PENN), Generac (GNRC), Caesars Entertainment (CZR) – The stocks will join the S&P 500 as part of the index's quarterly rebalancing. NXP jumped 8.1% in premarket trading, with Penn up 5.8%, Generac gaining 3.6% and Caesars climbing 4.8%.

Carnival (CCL) – Carnival CEO Arnold Donald told the Financial Times he sees at least two more tough years for the cruise industry. Donald said the cruise line operator's full fleet might be sailing by the end of the year but that it will take at least until 2023 for revenue to return to pre-Covid levels. Carnival rose 1.2% in the premarket.

AMC Entertainment (AMC) – AMC will begin reopening movie theaters in Los Angeles, starting with two locations today. It plans to open the remaining 23 theaters in Los Angeles on Friday, and hopes to have all 56 California locations open by then depending on local approvals. AMC jumped 8.7% in premarket trade.

Shaw Communications (SJR) – The Canadian communications company agreed to be bought by rival Rogers Communications for C$26B including debt ($20.9B in US Dollars). Shaw's U.S. shares surged 53% in the premarket.

Ford Motor (F) – Ford will recall 2.9 million vehicles to check for potentially faulty driver-side Takata airbags. The National Highway Traffic Safety Administration had called on Ford to do so in January, and the automaker plans to begin notifying owners on April 1.

Gilead Sciences (GILD), Merck (MRK) – The drugmakers will study a combination of their experimental drugs to treat HIV. Gilead and Merck will look at the effectiveness of the drug cocktail even when taken only every few months.

Eli Lilly (LLY) – Eli Lilly said its experimental treatment for Alzheimer's modestly slowed decline in patients over an 18-month period in a mid-stage study. Lilly has already begun a second study of the treatment. Lilly fell 5.3% in the premarket.

Lordstown Motors (RIDE) – Lordstown said it will issue a "full and thorough" statement in the coming days that the electric truck maker said would refute a critical report by short-seller Hindenburg Research. Lordstown has said the report contains "half-truths and lies." Its shares rose 5.9% in premarket trading.

XPeng (XPEV) – XPeng got a $76.8 million investment from the provincial government in Guangdong, where the Chinese electric vehicle maker is based and has two manufacturing plants. XPeng added 4.2% in premarket action.

Dollar General (DG) – The discount retailer was upgraded to "overweight" from "neutral" at Atlantic Equities, which cited valuation as well as a positive impact from stimulus check spending and continued market share gain.

AstraZeneca (AZN) – Ireland became the latest country to suspend the use of AstraZeneca's Covid-19 vaccine, following reports out of Norway regarding blood clots in some patients. Officials said they took the action "out of an abundance of caution," although AstraZeneca said its review of more than 17 million people showed no increased risk of blood clots.

United Airlines (UAL), American Airlines (AAL), Delta Air Lines (DAL), Southwest Airlines (LUV) – Airline stocks are gaining ground after the Transportation Safety Administration said airport screening levels are now at one-year highs. Separately, Southwest said passenger demand is continuing to improve this month. United was up 3% in the premarket, American gained 4.3%, Delta rose 2% and Southwest edged up 1.3%.

DraftKings (DKNG) – The sports betting company announced a proposed offering of $1 billion in convertible notes due in 2028. DraftKings fell 3.5% in premarket trade.