(Reuters) - Standard & Poor's Ratings Services lowered its sovereign rating on Greece to 'CCC minus' from 'CCC', saying the probability of Greece exiting the eurozone was now about 50 percent. Greece's bailout talks with lenders collapsed over the weekend, intensifying fears that the country could soon exit the euro zone. A Greek official told Reuters on Monday the country would not pay a 1.6 billon euro loan instalment due the International Monetary Fund on Tuesday. S&P said according to its assessment Greece would likely default on its commercial debt during the next six months. ...