The world’s biggest share registry Computershare expects first half earnings to fall about 15 per cent from a year earlier because of tough and volatile markets.

That would be equivalent to management earnings per share for the six months to December falling to about 22.9 cents, from 26.96 cents a year earlier.

The earnings before interest, tax, depreciation and amortisation (EBITDA) margin would also decline, Melbourne-based Computershare said in a statement on Wednesday.

The company added that it expected recent takeovers to contribute to earnings, with Serviceworks and SLS to contribute five cents to management EPS on an annualised basis.

There would also be $US70 million in synergies from Bank of New YOrk Mellon Shareowner Services after three years.

Computershare also said the outcome of the antitrust investigation of the BSS acquisition had only been known for a few days and markets remained volatile, so the company was not in a position to provide full year guidance.