All mine!G 30

Can be done easily in Free Mode. Start a game with initial capital set to 3 million and make sure you have 3 competitors. Other settings don’t matter but I set the pause mode to manual so I could pause.

Go into the Company section of the actions menu and tab over to Banking activities. Go to current bonds and issue the largest bonds you can. Then tab over to Competitors and highlight the competitor with the least valuable company. Press Y to merge with them and the achievement should pop.