Investing.com - The European Central Bank cut all three of its interest rates and expanded its asset-buying program on Thursday..The euro tumbled on the stronger-than-expected actions to boost the economy and stop ultra-low inflation becoming entrenched.The ECB cuts its deposit rate deeper into negative territory and increased monthly asset buys to €80 billion from €60 billion.Surprising markets, it also cut its main refinancing rate to zero from 0.05%.The ECB said it would also start buying corporate debt and would also launch four new rounds of cheap loan packages.