* ConvaTec Group and Smurfit Kappa to join FTSE 100
* Polymetal International and Travis Perkins to leave FTSE 100
* Ferrexpo, Newriver Reit, Nostrum Oil & Gas will enter FTSE 250
* Countrywide, DFS Furniture, Laird, NCC Group will leave FTSE 250
Nov 30 (Reuters) - Precious metals mining company Polymetal International Plc and Travis Perkins Plc, Britain's biggest supplier of building materials, will drop out of the benchmark FTSE 100 index and become a part of the FTSE 250.
Medical products maker ConvaTec Group Plc and packaging products maker Smurfit Kappa Group Plc will replace these companies in the bluechip index. bit.ly/2gJlYVO
In the FTSE midcap index property services company Countrywide Plc, upholstery retailer DFS Furniture Plc , wireless parts maker Laird Plc and cyber-security firm NCC Group Plc will be replaced by iron ore miner Ferrexpo Plc, real estate company Newriver REIT Plc and oil exploration company Nostrum Oil & Gas Plc.
Travis Perkins had warned in October that it would not meet market expectations for full-year profit, blaming a disappointing performance in its plumbing and heating business.
Polymetal, which pushed house-builder Berkeley Group Holdings Plc out of the FTSE 100 index in August, has been pushed out of the index despite a surge in its share price as economic uncertainty had driven up the price of gold. The company's share price had risen just over 30 percent year-to-date.
Getting into the FTSE 100 can often fuel further demand for a company's shares, since funds that track the FTSE or invest in the index can then add that stock to their portfolio, while the inverse is true if a company falls out of the FTSE 100.
The rankings are decided on market capitalisation. Companies with the lowest market cap in the FTSE 100 drop into the FTSE 250 mid-cap index, and vice versa.
The changes will be implemented at the close of business Friday, Dec. 16 and take effect on Monday, Dec. 19. (Reporting by Sanjeeban Sarkar in Bengaluru; Editing by Shounak Dasgupta)