Generally, both the purchaser and seller must file Form 8594 and attach it to their income tax returns (Forms 1040, 1041, 1065, 1120, 1120-S, etc.)
The following tax forms are typically used when selling a business: Form 8594, Asset Acquisition Statement. Form 4797, Sales of Business Property.
If the amount allocated to any asset is increased or decreased after the year in which the sale occurs, the seller and/or purchaser (whoever is affected) must complete Parts I and III of Form 8594 and attach the form to the income tax return for the year in which the increase or decrease is taken into account.
In simple terms you can say that acquisition is an act of one company taking over or acquiring another company's controlling interest. This can be done either by buying assets of that company or buying shares or stocks of the company.