The U.K. approves a Covid-19 vaccine developed by Pfizer and its partner BioNTech; Salesforce is buying Slack for $27.7 billion; McDonald’s McRib sandwich is back for a limited time.

By Joseph Woelfel, The Street–

Here are five things you must know for Wednesday, Dec. 2:

1. — Stock Futures Point Lower

Stock futures pointed lower Wednesday, a day after the S&P 500 and Nasdaq both set record highs.

Contracts linked to the Dow Jones Industrial Average fell 95 points, S&P 500 futures slipped 6 points and Nasdaq futures declined 14 points.

Stocks finished higher Tuesday with the S&P 500 and the Nasdaq both closing at records as Wall Street came off a November that was its best monthly performance since April.

The S&P 500 finished up 1.13% to 3,662, and the Nasdaq rose 1.28% to 12,355. Both indexes also posted intraday all-time highs. The Dow gained 185 points, or 0.63%, to close at 29,823.

Driving the stock market gains have been breakthroughs on the creation of a coronavirus vaccine. In the latest development, a Covid-19 shot from Pfizer  (PFE) – Get Report and its German partner BioNTech  (BNTX) – Get Report was approved in the U.K., making Great Britain the first western country to grant approval for a vaccine.

Asian stocks ended Wednesday’s session mixed. President-elect Joe Biden told The New York Times he wouldn’t immediately ease tariffs on Chinese goods.

For more on Asian markets read:

Buying Frenzy Sends Shanghai Gauge of 50 Large Stocks to 12-Year High as Traders Bet on Cyclical Stocks to Outshine Technology

2. — Pfizer Covid Shot Approved by the U.K.

Pfizer was rising nearly 4% in premarket trading after the U.K. approved a coronavirus vaccine developed by the U.S. drugmaker and its German partner BioNTech.

The decision by the U.K. to approve the vaccine for emergency use came ahead of expected approvals from the U.S. and the European Union.

The shot will be available in Britain starting next week.

“The government has (Wednesday) accepted the recommendation from the independent Medicines and Healthcare products Regulatory Agency to approve Pfizer-BioNTech’s Covid-19 vaccine for use,” the U.K. said. “The vaccine will be made available across the U.K. from next week.”

Pfizer Chairman and CEO Albert Bourla called the authorization an “historic moment.”

“This authorization is a goal we have been working toward since we first declared that science will win, and we applaud the MHRA for their ability to conduct a careful assessment and take timely action to help protect the people of the U.K.,” he said.

The Pfizer/BioNTech vaccine was shown in trials to be 95% effective in preventing the virus.

Pfizer rose 3.53% to $40.80 in premarket trading. American depositary receipts of BioNTech rose 6.64% to $121.58.

3. — Salesforce to Buy Slack for $27.7 Billion

Shares of Salesforce.com  (CRM) – Get Report were lower in premarket trading Wednesday after the cloud giant said it was buying Slack Technologies  (WORK) – Get Report for cash and stock in a deal valued at $27.7 billion.

The acquisition had been widely anticipated after word of talks between the companies first surfaced last week. The deal will combine Slack, a highly visible messaging platform with Salesforce, a maker of productivity tools used by companies to improve sales and services.

The acquisition is Salesforce’s largest ever. It’s expected to close by the end of July.

Slack shareholders will receive $26.78 in cash and 0.0776 a share of Salesforce common stock for each Slack share, representing a 55% premium to Slack’s price on Nov. 24, the day before reports surfaced about a potential deal.

“This is a match made in heaven,” said Marc Benioff, chairman and CEO of Salesforce. “Together, Salesforce and Slack will shape the future of enterprise software and transform the way everyone works in the all-digital, work-from-anywhere world. ”

Slack has been facing increased competition from Microsoft  (MSFT) – Get Report, which has seen rapid uptake of its Teams app, which offers similar tools to Slack.

“Make no mistake: We like this deal for Salesforce,” said Jim Cramer and the Action Alerts PLUS team, which holds Salesforce in its portfolio.

Salesforce, meanwhile, reported third-quarter earnings that topped analysts’ forecasts but issued guidance that was short of expectations.

Salesforce shares fell 4.66% to $230.10 in premarket trading. Slack was down 1.3% to $43.27.

4. — Wednesday’s Calendar: ADP Jobs Data, Snowflake Earnings

The economic calendar Wednesday includes MBA Mortgage Applications for the week ended Nov. 27 at 7 a.m. ET, the ADP National Employment Report for November at 8:15 a.m., Oil Inventories for the week ended Nov. 27 at 10:30 a.m. and the Federal Reserve’s “Beige Book” at 2 p.m.

Federal Reserve Chairman Jerome Powell and Treasury Secretary Steven Mnuchin testify before Congress for a second day, beginningat 10 a.m.

Earnings reports are expected Wednesday from Snowflake  (SNOW) – Get Report, Zscaler  (ZS) – Get Report, PVH  (PVH) – Get Report, Splunk  (SPLK) – Get Report, Crowdstrike  (CRWD) – Get Report, Okta  (OKTA) – Get Report and Five Below FIVE.