As others have pointed out, there are often many factors that are contributing to a stock's movement other than the latest news. In particular, the overall market sentiment and price movement very often is the primary driver in any stock's change on a given day.
But in this case, I'd say your anecdotal observation is correct:
All else equal, announcements of layoffs tend to drive stock prices upwards.
Here's why:
To the public, layoffs are almost always a sign that a company is willing to do whatever is needed to fix an already known and serious problem.
Mass layoffs are brutally hard decisions. Even at companies that go through cycles of them pretty regularly, they're still painful every time. There's a strong personal drain on the chain of executives that has to decide who loses their livelihood. And even if you think most execs don't care (and I think you'd be wrong) it's still incredibly distracting. The process takes many weeks, during which productivity plummets. And it's demoralizing to everyone when it happens.
So companies very rarely do it until they think they have to. By that point, they are likely struggling with some very publicly known problems - usually contracting (or negative) margins.
So, the market's view of the company at the time just before layoffs occur is almost always, "this company has problems, but is unable or unwilling to solve them.".
Layoffs signal that both of those possibilities are incorrect. They suggest that the company believes that layoffs will fix the problem, and that they're willing to make hard calls to do so.
And that's why they usually drive prices up.
