3i Group, the UK listed alternative assets firm whose chief executive Philip Yea was replaced this morning, wrote down its 50 largest assets by more than a fifth, increasing its leverage to near 70% and adding to concerns about the firm’s high levels of debt.

3i's debt levels increased from 50% to approaching 70% relative to its portfolio value in the three months to the end of December, according to estimates by US bank JPMorgan Cazenove from information in 3i's interim management statement published today.