The investment firm Alliance Trust has grown its net asset value (NAV) in the first six months of the year despite headwinds from a UK recession and the Eurozone debt crisis.NAV per share in the six months to the end of June rose 5.5% to 432.2p, beating the group's benchmark global growth sector index, which returned 5.3%Against similar investment trusts (known as the global growth peer group) Alliance came 13th out of 33.The group has also announced it will pay £1m to take Aviva Investors 'sustainable and responsible investment' (SRI) fund in house. A team of five Aviva staff will move into Alliance's offices, bringing with them £1.2bn in funds.Katherine Garrett-Cox, Chief Executive of Alliance, said the deal with Aviva was "significant" and added, pointedly, that her group's NAV "continues to outperform the Global Growth sector".The shares were down 0.4% by 8:07.BS