SHANGHAI, Dec 31 (Reuters) - China stocks rose to multi-year highs on the last trading day of 2020, as investors cheered a Sino-Europe investment deal and Beijing’s policy support for its capital markets. The blue-chip CSI300 index closed up 1.9%, at 5,211.29, the highest level since June 15, 2015 while the Shanghai Composite Index gained 1.7% to 3,473.07, its highest since Feb. 5, 2018. Major indexes posted robust yearly gains, with Shenzhen’s start-up board seeing its strongest year since 2015, thanks to the economy’s recovery from the coronavirus pandemic and policy support. The European Union and China agreed on Wednesday to an investment deal that will give European companies greater access to Chinese markets and help redress what Europe sees as unbalanced economic ties. “The deal exceeds market expectations and has a profound impact,” said Yan Kaiwen, an analyst with China Fortune Securities. Also boosting sentiment, China said on Wednesday it planned to increase the proportion of the country’s annuity funds that can be used to invest in equities, which could inject 300 billion yuan ($45.95 billion) into markets. For the month, CSI300 rose 5.1%, while SSEC firmed 2.4%. For the year, CSI300 gained 27% and SSEC 14%. The tech-heavy start-up board ChiNext rose 63% in 2020, posting its biggest yearly gain since 2015, versus a 43% gain for Nasdaq. “The strength in the start-up board reflects a change in China’s economic structure, as the country is shifting to high-quality development,” said Niu Chunbao, chairman at Wanji Asset, a Shanghai-based private securities fund. Analysts and traders said the solid gains in the market were also supported by the recovery in China’s economy from the pandemic lows. The country’s economy is expected to expand around 2% in 2020, the weakest pace in over three decades but stronger than other major economies struggling to contain infections. ($1 = 6.5290 Chinese yuan)