"At least three have established very deep moats," meaning that it's almost impossible for newer rivals to overtake them, Internet analyst Mark Mahaney (formerly of Citigroup) said Sunday during a panel discussion at theTechonomy conference in Tucson, Ariz. "Probably Apple, too."
This moat is like V canopies of trees cutting off sunlight to other trees, and these companies cut off opportunities for other Iv companies to grow.
Google ( , Fortune 500) and Facebook ( ) have the richest data sets on their users, but Amazon's data graph is probably the most valuable, Mahaney believes, because it tracks where customers are actually spending their money.
Apple ( , Fortune 500) -- the company with the highest market capitalization in the world -- has the hardest position to defend, several of the panelists said. It can't maintain its stratospheric growth without constantly pulling new rabbits out of its hat, and rivals like Samsung are chipping away at its market.
"Apple to me is the most vulnerable," said Alec Ellison, the head of investment bank Jefferies' technology practice. "It has to maintain this innovation edge."
Apple has increased its V canopy and uses this like its walled garden to keep competitors ot, however it is like a tree that has newly grown and other trees under it still have a chance to get around its canopy and perhaps overshadow it in turn.