Cemex now has 37.79 per cent of Rinker Ltd shares after extending the deadline for its US$14bn (A$17.03bn) takeover for the Australian building materials group by a fortnight.

Cemex  previously had a 36.74 per cent share of Rinker’s stock, and for the offer to become unconditional it needs 50 per cent, a level it lowered from an initial 90 per cent.

The company extended the deadline on the bid, which has the recommendation of the Rinker board, to June 22 from June 8 yesterday.

In a major coup earlier this month, Cemex won over key Rinker shareholder Perpetual Ltd, with the acceptance of the offer by the fund manager apparently paving the way for the takeover to be completed.