"Going in with 10% would be futile and bring notice to anyone else to make a bid." True, but as you say they reach a deal, and too often I've seen an offerer revealing having 19 or even 29% ownership at the time of the offer being announced but not having revealed that they even had 10% of outstanding shares before. In such cases two or three entities sold to them just prior to the offer. Many devious things happen under the sun when there is money involved.