Here is a thought. The more major merchants that accept bitcoin the wilder the exchange rate will be. Merchants especially large one won't keep the coins they have to convert right away so that means large dumps on exchanges that might not get bought. Or I could be wrong.
Planning to buy a billion dollar TV?
I'm not but people generally shop at predictable times of day. Newegg isn't worldwide and no merchants that currently are announcing that they are accepting bitcoin actually are planning to keep the bitcoins. So either it's just publicity which is more likely because otherwise newegg would have to cash out a large amounts of coins on an exchange. Maybe there are bids to buy them all and maybe not. It adds to volatility. All these companies getting interested is great for bitcoin exposure but they aren't interested in keeping bitcoins as far as I have seen.
[Damn.. looking for the interview that had it and can't find it right now. However...] Tony Gallippi has stated that some merchants at least (seem to recall he said "many") keep at least a small fraction of their sales in Bitcoin. I know the Bitpay interface does allow for that (converting some, not all, of the Bitcoins directly into cash, and holding the remainder as BTC).
Any particular reason? Is that like to handle refunds? Or as an investemnt for a company?
From my interpretation of it, it sounded like merchants that held some were interested in holding for investment. After all most companies up to now decided to accept because the wanted to, not to keep up with competition. So I think they have at least some belief long term. Of course they need to convert a certain amount to cover expenditures, but it sounded like many kept part of the profit as bitcoins. (Still haven't found that link...)
EDIT: Found this link, although I know this wasn't the one I was looking for:
One can also accept bitcoins through BitPay and take bitcoins, either fully or a portion of the sales. Our company is an integrator partner with them, and we know that not all merchants do the fiat conversion. But it's true that only true Bitcoin believers do that. It should change through time though, since it's quite beneficial for companies to simply hold as much bitcoins as humanly possible.