Platts is not a spot price setter. Its an index! Platts, like...

Platts is not a spot price setter. Its an index! Platts, like most IO price reporters (eg, MB), gathers the day's IO trades to construct an index price. Different index providers use different trades throughput the day, so by definition their derived (reported) spot price for the day will be different. Discussion around who is reporting the "right" spot price is meaningless if you understand this.

Live data shows that the price for a boat load of IO can vary by as much as $5/t (but typically about $2/t) on any given day for the same grade/type of IO. Whats important is the general trend of the indices.

Perversely, some iron ore producers, like AGO and even Rio, use the index to sell their iron ore. When this is the case, it is usually done on a 3 month rolling average basis. Any IO price movement you see today is unlikely to feed in to a producer's bottom line for some time. It is usually only the smaller "odd batch" or spot market IO producers who are completely open to daily bidding - although this may include big producers who have out of spec or excess production not covered by longer term supply agreements.