Investors in high-flying, data-crunching services provider Appen worry that it will take time for its takeover of a rival to boost profits but largely welcome the deal as a way to reduce the company's reliance on a small number of large tech company clients.

Appen shares lost 9.2 per cent to $22.14 on Tuesday after they emerged from a trading halt put in place the previousr day to allow for a $285 million capital raise to fund its purchase of the machine-learning software business Figure Eight. The stock is still up 128 per cent in the past year and closed above the raising price of $21.50 a share.