bid (something) down
To decrease the value of something, usually a security, by offering to pay lower and lower prices for it. Only buy that stock if you are able to bid it down first.
bid something down
to lower the value of something, such as stock, by offering a lower price for it each time it comes up for sale. We bid the price down and then bought all of it. I could see that the traders were bidding down the price, but I didn't want to take the risk.