The spread is the difference between the bid price and the ask for a stock.
In the case of JDO, when I looked at the detailed transactions I saw this.
Bid
.023 1,000
.022 500
.022 400
.021 2,000
.021 2,500
.02 15,000
Ask
.025 800
.025 300
.026 2,000
.026 1,500
.028 2,600
.030 20,000
Yes transactions were taking place in fractions of a penny.
This information is typically called Nasdaq Level 2, ask your broker about obtaining it.
I get it free but than I have a decent amount of assets (albeit a lot less than a year ago) and typically make several transactions a month.
So if you wanted buy $500 worth at $.02 you'd put a limit order in for 25,000 at .02.
The problem is you wouldn't actually get all 25,000 shares instead you might only get 2-3,000 shares on a given day which is only $40 $60, then if you sold them later that day or the next day for your .03 you be only selling for $60 to $90. You'd be out $10 in commissions. Typically less than $1,000 of JDO stock gets traded in a day. Which makes sense, the market value for the whole company is <$600K. Overpriced for a bankrupt company.
But if you have $500 burning a hole in your pocket trying to day trade a penny stock is actually a pretty cheap investment lesson. It will give you a some good insight into how illiquid stock behave and probably more entertainment value than roulette wheel at a casino.
If you are willing to wait a few months I think you'll be able to do the same thing with GM stock, although you may have to spend $.20 not $.02 a share.
I see you are only 19 so let me change my advice, since $500 is probably real money at your age and day trading penny stock you are almost certain to lose it. The general advice for a young dreamer is to stick money in a 401K/IRA with index fund. This is really good advice but frankly it is boring as hell. If I was force to buy only mutual funds when I was your age I never would have retired. Instead I'd take the $500 do some research and buy a stock, and I continue doing this as I accumulated $500 or so. You still want to fund your IRA or if you have a 401k fund that.
There are tons of amazing stocks on sale right now. The trick is to find them. Obviously, I don't have the magic formula but I have some clues. You previously mentioned CX and GE both of these are good choices (even if the stock price has continued to go down). Cemex any particular is good choice, partly because unlike GE it is not a household name. A couple of investment newsletter that I subscribe to have recomended it. It has taken on too much debt which could prove deadly in this environment. But fundamentally it is a profitable company, which is selling well below its book value. Of course right now it is in the wrong business at the wrong time, but eventually that will change. So whatever you did that caused you to ask about CX, do more of that. Come back with your top couple of stock picks ask the old fogies for our opinions and we will be happy to provide them.
If you need advice the FAQs have long list of recommended investment books. I think with a couple of books (I assume you are good at math) and some screen tools available on the web you can find good values out there. I'd concentrate on smaller companies those with less than $<1 billion in market cap or sales, but I'd avoid penny stocks. Fundamentally the problem with a company like JDO is they are bankrupt so you have moved from invested to pure speculation. CX is nice compromise there is a chance it will go back up to 40 in the next year or so...
