Seasonal share prices?

Hi All,
First post here...
Been lurking for a couple of weeks, Still havent invested anything yet, although playing the ASX Sharemarket Game for a bit of experience first.
Trying to read up on FA and TA as much as possible but very little experience/knowledge as yet.

Anyways, first question to the board...

Are share prices influenced by seasonal changes? (time of year/month)

I know alot of organizations have much higher profit margins leading up to christmas to example (I work for a Pharma company and we make alot more profit over spring summer suplying drugs for european winter) so does these higher seasonal profits influence the share price?

Would be a good study for a research student I guess.

I'd hazard a guess and say perhaps retailers like JBH, DJS might rally into Dec
I think there is some seasonality in Apple in the states.

Funny, I was actually thinking about this during the day today.

I've used seasonality for some time and it can yield some quite advantageous results by itself and combining with other styles of strategies.