Rio Tinto is negotiating contracts to supply iron ore priced on a quarterly basis, a shift from the annual benchmark pricing system.
Rio, which was one of the companies that said it preferred the benchmark pricing system, will join BHP Billiton and Vale if it moves to shorter term contracts.
Last month it said it would sell iron ore to most Asian steel mills on a short-term basis, abandoning the annual system.
Vale also announced it had closed iron-ore deals with 97% of its client base under its new quarterly contract system.
The shift from 12-month contracts comes after last year's failed talks between Rio and China, and when mining companies rejected Chinese demands for steep discounts on the prices already agreed with Japanese and South Korean steel mills.
Rio Tinto did not disclose any further details on short-term pricing as discussions are still underway.