One justification is that spending on new shares gives them a higher return than spending on old.

When you spend on old, someone with no further interest in Uber has money in their pocket.

When you create new ones, you've just injected money into Uber, which increases its likelihood of survival.

If they are buying enough to get control, they can now choose to spend that $1 billion in ways that channel money back into other companies that they own. Thereby further reducing the cost to them of providing that money. (Presumably, though, the money channeled back will be for products that help Uber. This looks like a shell game but isn't.)

I don't want to spam this article all over, but Matt Levine, also at Bloomberg, I felt had a much better overview of that question almost verbatim, plus imo he's an excellent writer.

https://www.bloomberg.com/view/articles/2017-11-16/softbank-...

The new ones are presumably the most senior class, and would likely come with rights such as liquidation preferences that would make them have a higher expected value (in the eyes of Softback).

There doesn't have to be any justification. Maybe they're hoping enough early investors want to lock-in their paper profits that they'll accept the offer.

I’d guess liquidation preference for the newly issued shares.

One is an investment and infusion of capital. The other is purchasing somebody else's investment that doesn't do anything for the company's cash.

Pretending real hard this isn’t a down round?

Maybe they figure early institutional investors with Series A, B, C, ... realize their shares will lose out in a liquidity event to preferential treatment for those with later shares, and so will be willing to sell their early shares for less.