LONDON, Aug 6 (Reuters) - London Stock Exchange Group (LSEG.L) reported a sharp rise in first-half revenues on Friday, along with progress integrating data group Refinitiv and a dividend increase, triggering the best daily performance in its shares so far this year. British stock exchange operator LSEG said its total revenue rose 4.6% to 3.36 billion pounds ($4.7 billion), helped by a 9.6% rise in capital markets revenue as listings enjoyed their best first half since 2014, and higher fixed income volumes. Shares in the 300-year-old bourse were up 6.3% at 1300 GMT, marking their best day since December 2020 and topping the blue chip FTSE 100 index (.FTSE) and Europe"s STOXX 600 (.STOXX). "We have had a terrific first half of the year - capital raising is very robust and a number of companies have been coming to market," chief executive David Schwimmer told reporters after LSEG said its operating profit jumped to 1.17 billion pounds from 457 million pounds a year earlier. Schwimmer said he expected the rest of 2021 to remain busy for initial public offerings (IPOs) and a modest number of special purpose acquisition companies to list. The CEO is trying to transform LSEG into a one-stop shop for data, trading and analytics with its $27 billion takeover of Refinitiv. But the costs of absorbing the data provider have worried some investors and its shares are down 20% since early March when it gave more details on the integration. read more The group said that about 77 million pounds of cost savings from the deal have been realised so far. It saw those rising to 125 million pounds by the end of the year, up from its previous 88 million pound forecast. "Progress with run rate synergies looks faster than anticipated," Credit Suisse analysts said in a note, adding that the estimated cost growth in the "low single digits" for 2022 and 2023 should also reassure the market. LSEG said that it expected further cost increases in the second half of 2021, caused by the return of costs, such as travel, that were affected by the coronavirus pandemic as well as ongoing expenses from legacy IT and inflation. It said it would pay an interim dividend of 25 pence per share, a rise of 7% from a year ago. Schwimmer said the company had identified and was addressing the cause of problems with Refinitiv"s news and data platform Eikon after a number of outages. read more Refinitiv was carved out from Thomson Reuters, parent of Reuters News, in 2018 by a consortium led by Blackstone (BX.N) before being bought by LSEG in a deal finalised in January 2021. Thomson Reuters now holds a minority stake in LSEG and Refinitiv pays Thomson Reuters for news it distributes. ($1 = 0.7184 pounds)