The lira eased to 1.8542 against the dollar by 1030 GMT, its weakest level since last June, from 1.8466 late on Monday. Analysts said the sell-off was due to profit-taking after the long-awaited rating upgrade.
Moody's assigned Turkey a Baa3 rating with stable outlook on Thursday making it eligible for inclusion in a number of investment-grade-only bond indices and reinforcing the economy's progression from emerging to developed market status.
Fitch Ratings raised Turkey to investment-grade in November, while Standard & Poor's rates it one notch below the cut-off.
Turkey's main share index, which has surged 18 percent this year, was up 0.68 percent, after falling almost 2 percent on Monday. It outperformed the main global emerging markets stock index.
The two-year benchmark bond yield rose to 5.10 percent from 4.92 percent on Monday. It hit an all-time low of 4.61 percent on Friday after the central bank cut key interest rates by 50 basis points.