Completion Bond: a form of insurance offered by a completion guarantor company (in return for a percentage fee based on the budget) that is often used to guarantee that the producer will complete and deliver the film
Some financiers require there to be a completion bond on a film to ensure that the film gets made. Often, this is done for higher budget independent films in the multiple millions, and often ones that already have a deal with a distributor in which they are given a minimum guarantee (aka the producer will get a guaranteed amount for the film as long as the film is completed).
During production, bond companies come in and monitor everything you do. They aren't necessarily the enemy; in fact, the last thing they want to do is take over the project.
Some savvy investors may ask you if you have a completion bond. We do not, and most films of our budget range also do not because a completion bond takes around 3-5% of an already tight budget. So, how can you give your investors some measure of comfort? Be responsible. Budget for a good-sized contingency. It may not be 10%, but it should be high. Trying to fool your investors will get you nowhere.