The pharmacy mega-giant shot up 18% on Tuesday following The Wall Street Journal's report, raising the company's value by about $1.5 billion.

If Walgreens Boots Alliance follows through with a sale to private equity, the company might join other healthcare deals under scrutiny for selling out to such investors.

Deal would cap tumultuous run for retailer whose market value shrank from a peak of over $100 billion to below $8 billion.