The size of the suit represents the amount Walgreens had invested in the beleaguered blood testing company, once valued at $9bn.

Health retail chain Walgreen has sued US-based blood testing technology developer and portfolio company Walgreen for breach of contract, the Wall Street Journal reported on Tuesday, citing people familiar with the matter.

Walgreen is suing for $140m, the sum being equal to the amount it has invested in Theranos. The companies formed a partnership in 2013 that would have involved Theranos blood testing being offered in Walgreens pharmacies across the US.

However, Walgreens claims Theranos misled it with regard to…