In US treasury auction (for bonds and notes), my understanding is that the highest bidder's price (and rate) is applied for all the buyers.
Assume a buyer 'A' who plans to buy a smaller number of bond shares. Let two other players 'B' and 'C' invest heavily compared to 'A. Let 'B' and 'C' be competitors of 'A'.
Is it possible for 'A' to invest low but bid high thus play spoilsport for 'B' and 'C'?