Check out the companies making headlines midday:

Apple — Apple rallied 4.8% to become the second-best performer in the Dow Jones Industrial Average, after Oppenheimer upgraded the tech giant to an outperform rating. Oppenheimer called Apple a “recurring revenue machine” and said its products and strong balance sheet should help it withstand any economic uncertainty due to the coronavirus.

Twitter — Shares of the social media company surged more than 8% following news that Elliott Management founder and billionaire investor Paul Singer is seeking to replace Twitter CEO Jack Dorsey. CNBC learned Elliott thinks Dorsey’s attention is split between running both Twitter and Square.

JPMorgan Chase — JPMorgan rose 1.4% on Monday morning despite falling interest rates after the bank was upgraded to overweight from neutral at Piper Sandler. “If the macro-environment proves to be as sustainably difficult as implied by a record low 10-year Treasury yield, we would expect JPM shares to continue outperforming peers as the ‘strong get stronger,” Piper Sandler said in a note to clients. The firm held its price target for the stock at $149 per share, about 27% above where shares were trading Monday.

General Electric — Shares of the embattled industrial company rose more than 1% after JPMorgan’s Stephen Tusa, who gained a following on Wall Street for his work on GE after his negative call in May 2016, upgraded the stock to neutral from underweight. Tusa said GE’s recent outperformance is due to two straight quarters of better-than-expected free cash flow, something he underestimated. The firm also raised its price target to $8 from $5, which is still below its current levels.

SmileDirectClub — Shares of the tele-dentistry company fell nearly 4% following a downgrade to neutral from buy from UBS. The firm said SmileDirectClub needs to show that it can sell its clear aligner products in a model that can generate profits. “Until we see an economic model that works, we believe the risk reward is balanced given incremental sales growth only puts strain on the balance sheet,” said UBS.

Verizon — Verizon climbed 3.8% after the telecom giant was upgraded to outperform from market perform by Cowen. The analysts said in a note to clients that the recent sell-off has made Verizon’s dividend yield more than 3 percentage points above the yield on the 10-year Treasury, and that spread is the widest since 2012. Cowen also said that Verizon’s investments in 5G should help the stock bounce back.

Activision Blizzard — The video gaming company’s stock rose more than 2% after Stephens named it a “best idea” and raised its target to $72 per share, which represents a 21% rally ahead. The firm’s prior target was $67. Stephens said Activision Blizzard’s recent pullback presents an attractive buying opportunity.

Forty Seven — Shares of the immune-oncology company surged more than 60% after announcing it will be bought for about $4.9 billion in cash, or $95.50 per share. The deal is expected to close in the second half of 2020.

Co-Diagnostics — Co-Diagnostics shares jumped about 10% on news the company will provide coronavirus tests to laboratories in the U.S. The news follows a policy change to after the Food and Drug Administration issued a policy aiming to fast-track the development of coronavirus diagnostic tests.  

JD.com — JD.com shares rose about 11% after the Chinese online retailer said it expects revenue to rise at least 10% in the first quarter. The company said it’s benefiting from home deliveries as the coronavirus spreads around China.

Western Digital — Western Digital shares gained more than 6% after an analyst at Baird upgraded the company to outperform from underweight, noting memory chip prices for mobile devices should rebound in the second quarter.

—CNBC’s Pippa Stevens, Jesse Pound, Yun Li and Maggie Fitzgerald contributed to this report.