a2 Milk shares soar on sales guidance lift

Shares in a2 Milk have soared after it said it expects full-year sales revenue of approximately $NZ545 million, $NZ20 million more than predicted in April.

Shares in a2 Milk have risen as much as 9.4% after it lifted its full-year sales guidance. (AAP)

Shares in The a2 Milk Company have risen to record levels after it lifted its full-year sales guidance for the second time in two months due to strong demand for its infant formula.

The company on Friday said it now expects revenue for the 12 months to June 30 of approximately $NZ545 million ($A518 million), $NZ20 million more than it predicted in April.

Managing director Geoffrey Babidge said a2 made the move after reviewing financial results to May 31.

Shares in a2 Milk rose 34 cents, or 10.2 per cent, to $3.69 on Friday, building to a record high after gaining steadily during 2017.

They have now gained more than 75 per cent since the start of the calendar year.

The firm, which is dual-listed on the ASX and NZ exchanges, said it had been working with formula manufacturer Synlait Milk to up production for the remainder of the financial year.

Schedule changes also mean that a2, whose first-half profit of $NZ39.4 million was more than it made in the whole of the last financial year, will up marketing expenditure by $NZ10 million on the first half rather than the previously flagged $NZ15 million increase.