Portugal successfully managed to sell two-year bond Wednesday, while witnessed a severe increase in bond yields that marked the highest since the country joined the European Union.

The yield rose to 5.993 percent, compared with the previous 4.086 percent during the auction held in September 2010. Concerns rose that Portugal might actually seek bailout from EU and the IMF due to higher yields.

The 10-year bond yield rose to 7.78 percent, while dropping to 7.74 percent after the conclusion of the auction.