An effect is, always, a noun. One may speak of the rainbow effect, or special effects,or, if one is a fan of the electric guitar, an effects pedal like Ibanez’s legendary Let me Google that for you.

But one must not use effect as a verb, even as a space-filler, however clamorously your inner articled clerk implores you to do so. “Effect” is the weakest verb on the planet. Whatever you are intending to “effect” is almost certain to be a nominalisation of another, stronger, better, more respectable verb — undoubtedly more suited to the task you have in mind than effect.

Why say “effect the conversion of shares” when you mean “convert the shares”?
Why say “effect the delivey of a notice” when you mean “deliver a notice”?

{c2|Metaphor|Plain English}}