A typical retail trader (a regular person just making a few transactions here and there on their lunch break) will likely follow a stock by looking at the price posted on mainstream stock-tracking websites, making any investment decisions from there. Professional traders go a little deeper.
Behind a stock's price, there's an intricate auction system of bid and ask. Bids represent orders to buy a stock and asks represent orders to sell (See: Bid and Asked). Tracking a bid tick means tracking the order flow on the bid side of the equation. Each bid tick indicates the movement in the bid price, whether moving higher or lower or holding steady.
A savvy trader can read the trend in the bid tick to garner micro advantages in the stock's movement. These kinds of additional benefits don't mean much for any particular trades (so aren't worth tracking for once-in-a-while types), but the additional value can add up over time if the trader is working in a high-volume environment.
Related or Semi-related Video
Finance: What is program trading?14 Views
Finance a la shmoop what is program trading? okay well watch two episodes of
Big Bang Theory if you first watch one episode of Keeping Up with the [Man and woman watching TV]
Kardashians deal alright no different kind of program trading, program trades
in a Wall Street sense are run by a computer program, hence the catchy name
and it's also called the black box like a program kicks out that if the S&P 500
is down 0.3 percent in an hour and the US dollar has risen relative to the
pound and goog is outperforming the tech index and the moon is in the seventh
house and Jupiter is aligned with Mars then short a million shares of GE like
that would be something that the box would tell you or something like that
and there are a ton of weird mathy things behind the rationale for each of [Math formulas appear]
these trades some of it makes sense to normal people but most of it needs three
PhDs in math and physics and other stuff to translate rationally
well the dangerous thing here about program trades is that usually there is
no human involved when they execute a trade that is it's just computers
talking to other computers but thankfully computers never have glitches [Computer chip blowing off steam]
right they never have mistakes and things generally always run smoothly
when computers are involved right well this is a really smart way to manage
your retirement money just give it all to a black box and assume the guys who
wrote the algorithm knew what they were doing or maybe not [Hacker using a PC]
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