The man who coined the term "Grexit" said the risks of a Greek exit from the euro zone have not gone away, despite the country having its credit rating upgraded on Tuesday.
"Now I thinkthe risks are not that much changed from where they were a year ago. Those risks have clearly not gone away and they won't go away for a number of years," Ebrahim Rahbari, director of global economics at Citi Research, who coined the term in February 2012, told CNBC.
"Back in February 2012 the chances that Greece was going to leave [the euro zone] were still going up - in fact they weren't all that high when I coined the term and then they went up a few months later," he told CNBC Europe's "Squawk Box."
Rahbari's comments come as Greece appeared more optimistic about its future. On Tuesday, the government announced that it hoped to return to the international debt market in 2014 and Fitch ratings lifted its credit rating on Greece to 'B-' from 'CCC.'
(Read More: Greece Reclassified as an 'Emerging Market')
Though still a junk rating, the upgrade will give the country another glimmer of hope that its harsh austerity program is having an effect. The yield on Greece's 10-year benchmark bond fell below 9 percent for the first time since 2010 on Wednesday and in another sign of ebullience, Greek Prime Minister Antonis Samaras was headed to China on a trade mission on Wednesday.
Rahbari said a "large part" of optimism over Greece has to do with markets discounting the risks posed by the country.