S&P cut its rating from "A+" to "A", while Moody's lowered its rating from "stable" to "negative". The former said it did not expect a significant recovery in profits over the next 24 months, while the latter said the company's cash flow was suffering as a result of investments in new medicines.
AstraZeneca's ownership of two of its top sellers, heartburn tablet Nexium and cholesterol-lowering drug Crestor, is set to run out before the end of next year, which will enable rivals to make much cheaper spin-offs of the medicines. As a result, the company has focused on improving its portfolio to counteract the negative impact.
But by investing in its pipeline of new medicines, Moody's said the British drug maker had lowered its cash flow relative to total debt.
In a statement, it said the change in outlook was prompted by the “weakening of AstraZeneca's credit metrics over the last 12 to 18 months”, with cash flow from operations/debt dropping to 36.5 per cent from 61.5 per cent at the end of 2013.
This was the result of material investments in the group's improving pipeline, material cash outflows from the restructuring of the business ahead of the genericisation of Nexium and Crestor in the US.
That said, Moody's did acknowledge that AstraZeneca's $2.7bn purchase of biotech firm ZS Pharma last week made “strategic sense”, as it will give the firm access to a novel compound for the treatment of blood disease hyperkalaemia – a “commercial advantage”.
Investors have not been perturbed by the news, with shares in the company currently down just 0.04 per cent at £41.57.