Meaning of “stratospheric trajectory” when referring to a company

Question

Source: Apple has had a successful decade. The next one looks tougher. (From The Economist (paywalled))

Given such achievements, Mr Cook could have retired amid gushing tributes around now (and with a spot in the billionaire club). Instead, he is likely to stick around at least until 2025, when his current stock grant will fully vest. This in turn raises the question of how long he can keep Apple on its stratospheric trajectory.

I wonder whether this means to keep Apple's stable development. Planes fly in stratosphere, because this is a stable layer of atmosphere. So I guess it means stability here.

Answer 1

Good reasoning. But I would say the stratosphere in this expression is used only because it's really, really high up. Hence, it means Apple's incredible growth (in value or prestige or market share).

Note that "trajectory" is used here to mean where something is aiming, so you can picture the plane still flying upwards towards the stratosphere, not coasting within it.

Another context where we talk about the stratosphere is baseball:

Wow! Look at that hit! That one's going into the stratosphere!

Answer 2

Stratospheric informally means extremely high or great

For example, if prices are extremely (maybe even unreasonably) high, you can say they are stratospheric.

The project had proved a stratospheric success.

Of all the blogs in the world, why did hers go stratospheric?

They begged to be in the national park because they saw it as a means of resisting wind farms and of preserving already stratospheric house prices.

Alas, they were mostly released at stratospheric prices, few wanted to pay.

Trust us, she's set to go stratospheric.

In your passage, it means Apple's skyrocketing (pun intended) growth/success.