European Central Bank Chief Mario Draghi can certainly move the markets - more than 6 percent higher in the case of Spain on Thursday. But his vow to save the eurozone has been criticised as a short-term "bluff".
Draghi told an investment conference in London that: "The ECB is ready to do whatever it takes to preserve the euro. And believe me, it will be enough."
He sought to calm financial markets after a volatile week that saw Spain borrowing costs once again reach an unsustainable record.
But while stockmarkets rallied following his remarks, some commentators accused the ECB of just stalling for more time.
Analysts say Draghi's comments signal that the ECB will intervene to support Spain and Italy but it is
uncertain whether they will resort to quantitative easing, or printing money, like Britain and the US.
The ECB's previous sovereign bond-buying programme received much criticism and was put on hold.
Draghi's speech also caused the euro to jump in value while interest rates on Spanish and Italian bonds fell sharply.