Rite Aid shares spiked by as much as 40% in trading on Tuesday after The Wall Street Journal reported that Walgreens was close to buying it.
Walgreens shares rose by about 4%.
Citing people familiar with the matter, The Journal said that a deal would value Rite Aid at close to $10 billion. The company's current market cap is about $6 billion.
At current prices, the combined market caps of Walgreens and Rite Aid — assuming the company is valued at $10 billion in a deal — would total about $112 billion.
This would make the combined company worth slightly less than CVS, the US's largest pharmacy chain, which has a market cap of about $116 billion.
Walgreens is scheduled to report quarterly results before the market opens Wednesday.
Here's a chart showing the surge in Rite Aid shares:
