Hi AMSH --
Right now, February 2009, the US is on standard time and Australia is on Daylight time. The US NYSE and all US floor trading opens at 9:30 AM in New York and closes at 4:00 PM. In Sydney or Melbourne those times are 1:30 AM and 8:00 AM, respectively. In Brisbane (no daylight time) -- 12:30 Midnight and 7:00 AM. In Adelaide -- 1:00 AM and 7:30 AM. In Perth -- 11:30 PM and 6:00 AM.
The volume is highest at the open and at the close. So you can trade the US markets if you either stay up late or get up early. If you are taking your signals at the close and trading at the close, the Australian morning corresponds with the US close.
If you have a trading system that uses end-of-day data and computes its signals after the close, there is a very large reward for taking the position on the close of the daily bar that gives the signal rather than waiting for the next day's open. You have to anticipate what the close will be, but there are many ways of doing that. For example, use real-time quotes and trade two minutes before the close; or compute the signal price in advance and place limit-on-close orders (providing your broker accepts them).
Almost all of my personal trading is done with Exchange Traded Funds that follow broad market indexes or sector indexes and that have average daily liquidity of US$100 million or more. I often use the leveraged ETFs. My holding periods usually range from intra-day to a few days, and sometimes as long as a few weeks. I also trade highly liquid options on broad market indexes. My positions are so small relative to the volume of the issue I am trading that they never move the market. You can do this from Australia.
The bid-ask spread on the broad market and sector ETFs is usually one cent on ETFS that range in price from $10 to $80. The bid-ask spread to purchase or sell the option is five cents or less (it can be as low as one cent if your broker uses "penny pricing" for options, otherwise five cents) on options priced at around $3.00 to $5.00.
Stocks that are very low in price cause any bid-ask spread, slippage, or commission to be a larger percentage of the trade than for a higher priced issue. But very low priced issues move a higher percentage more easily than higher priced issues do, so you might make that up easily. It is the liquidity that I would worry about more than the share price. Personally, I want to see $100 million per day, or close enough to it that the bid-ask spread is one or two cents. There are only a few stocks listed on the ASX that trade that much -- BHP, etc. I do not follow Australian stocks intra-day. You might want to do some studies using intra-day prices and bid-ask spreads. Let us all know what you find.
Thanks,
Howard