Did you ever wonder what would have happened to the Apple shares owned by Forrest Gump?
Well, I did. Possibly related to the fact that the share hit a new all time high today, closing on $665.15.
As it turns out, another guy has asked himself this question and has done all the bothersome legwork (no offence, Lieutenant Dan).
Some guy over at the oddly named blog Fancy Dress Costumes has backtraced a theoretical investment in Apple - Full story here
The key points
Since Dan and Forrest seem to have invested in Apple pre-IPO, the assumed investment is of 100,000 dollars.
On Sept. 23rd 1975 Apple send the following letter to Forrest:

Photo: FDC
The date of the letter is an inside joke, since Apple was fouded April 1st 1976.
The guys over at FDC assumes that Dan and Forrest participated in the first round of financing, in which investors got 15% equity for $500,000. Thus 100k would yield the investment-duo a whopping 3 percent of Apple.
Post-IPO that would result in about 1.47 million shares. Value on first day of trading would be 42 million dollars.
So forgetting the ups and downs, let's bring the number up to today. At $665.15, that would mean that Dan and Forrest $100,000 investment would be worth 7.8 billion dollars.
7.8 billion dollars
Source: fancydresscostumes