Porquê?

"Moody's Investors Service has today changed the outlook on the government of Portugal's Aa2 ratings to negative from stable*. The rating action reflects both the structural economic challenges facing the country, which have been exacerbated by the global crisis, and the apparent lack of motivation for policymakers to address them.
[…]
Moody's says that the most likely outcome for Portugal is a slow but inexorable decline, where growth remains sluggish, thereby stalling incomes, and where debt continues to build over time. Indeed, Moody's main concern is slow growth potential, which the rating agency attributes to the unwillingness of successive governments to take steps to restore competitiveness. The competitiveness gap is also generally seen as the cause of Portugal's large current-account deficits. Should this situation continue, the trend growth rate in the economy is likely to remain relatively low, thereby limiting the government's ability to 'grow' out of its debt problems even when the post-crisis recovery gets underway.
[…]
In the first decade of the single currency union, Moody's notes that Portugal's budget failed to meet the Growth and Stability Pact criteria multiple times and the authorities relied heavily on one-off measures. When the budget fell below the Pact's 3% ceiling, efforts were not made to move it upwards."

Porquê? Porque como diz o Nuno Branco "quem empresta tem olhos na cara."

*bolds meus