Large BUY LIMIT orders' effect on a stock's price
Traders sometimes look at the depth of the book (number of outstanding limit orders) to try and gauge the sentiment of the market or otherwise use this information to formulate their strategy.  If there was a large outstanding buy order at $49.50, there's a decent chance this could increase the price by influencing other traders. However, a limit order at $2 is like an amazon.com price of $200,000 for a book.  It's so far away from realistic that it is ignored.  People would think it is an error. Submitting this type of order is perfectly legal.  If the stock is extremely thinly traded, it might even be encouraged because if someone wanted to sell a bunch and did a really bad job of it, the price could conceivably fall that far and the limit order would be adding liquidity.  I guess.  Your example is pretty extreme. It is not uncommon for there to be limit orders on the book that are not very close to the trading price.  They just sit around.  The majority of trades are done by algorithmic traders and institutional traders and they don't tend to do this, but a retail investor may choose to submit an order like that, just hoping against hope. Also, buy orders are not likely to push prices down, no matter what their price is.  A sell order, yes (even if it isn't executed). If an offered price is below what people are willing to sell for, it is simply ignored. (What happens if I offer to buy lots of cars as long as I only have to pay $2 each? Same thing.)
The principle of demand-supply law will not work if spoofing (or layering, fake order) is implemented. However, spoofing stocks is an illegal criminal practice  monitored by SEC. In stock market, aggressive buyer are willing to pay for a higher ask price pushing the price higher even if ask size is considerably larger than bid size, especially when high growth potential with time is expected. Larger bids may attract more buyers, further perpetuating a price increase (positive pile-on effect). Aggressive sellers are willing to accept a lower bid price pushing the price lower even if ask size is considerably smaller than bid size, when a negative situation is expected. Larger asks may attract more sellers, further perpetuating a price fall (negative pile-on effect).  Moreover, seller and buyers considers not only price but also size of shares in their decision-making process, along with marker order and/or limit order. Unlike limit order, market order is not recorded in bid/ask size. Market order, but not limit order, immediately affects the price direction. Thus, ask/bid sizes alone do not give enough information on price direction. If stocks are being sold continuously at the bid price, this could be the beginning of a downward trend; if stocks are being sold continuously at the ask price, this could be the beginning of a upward trend.  This is because ask price is always higher than bid price. In all the cases, both buyers and sellers hope to make a profit in a long-term and short-term view I would say the most challenging fact for this assertion is that HFT firms operate with extremely limited capital bases. For a stock with say 10m shares ADV, even a very large and successful HFT strategy might use a position limit of no more than 5000 shares.  That is to say if you sum up and net the buys and sells for a stock across the day the HFT firm will never exceed 10,000 shares (2x position limits assuming it completely flipped) on a stock that trades 10,000,000 shares on a given day. The high volumes are attained through high turnover, the strategy might trade up to 500,000 shares (or 5% of the volume) attaining a 50x turnover.  But that brings me back to the original point. In the market microstructure literature market impact generally has been found to scale linearly or even sub-linearly for net volume executed.   If I alternate between thousands of 1 lot buy and sell orders, it would be very difficult for me to move the market because the market impact of every one of my buy orders roughly cancels the market impact of my almost exactly equal number of sell orders.   There might be a higher-order mechanism at work, but I'm genuinely curious what you think it might be. How could strategies that attain such small net positions have such out-sized impact on market direction? "Most of the investors who have large holdings in a particular stock have pretty good exit strategies for those positions to ensure they are getting the best price they can by selling gradually into the volume over time. Putting a single large block of stock up for sale is problematic for one simple reason: Let's say you have 100,000 shares of a stock, and for some reason you decide today is the day to sell them, take your profits, and ride off into the sunset.  So you call your broker (or log into your brokerage account) and put them up for sale.  He puts in an order somewhere, the stock is sold, and your account is credited. Seems simple, right?  Well...not so fast. Professionals - I'm keeping this simple, so please don't beat me up for it! The way stocks are bought and sold is through companies known as ""market makers"".  These are entities which sit between the markets and you (and your broker), and when you want to buy or sell a stock, most of the time the order is ultimately handled somewhere along the line by a market maker.  If you work with a large brokerage firm, sometimes they'll buy or sell your shares out of their own accounts, but that's another story. It is normal for there to be many, sometimes hundreds, of market makers who are all trading in the same equity.  The bigger the stock, the more market makers it attracts.  They all compete with each other for business, and they make their money on the spread between what they buy stock from people selling for and what they can get for it selling it to people who want it. Given that there could be hundreds of market makers on a particular stock (Google, Apple, and Microsoft are good examples of having hundreds of market makers trading in their stocks), it is very competitive.  The way the makers compete is on price.  It might surprise you to know that it is the market makers, not the markets, that decide what a stock will buy or sell for. Each market maker sets their own prices for what they'll pay to buy from sellers for, and what they'll sell it to buyers for.  This is called, respectively, the ""bid"" and the ""ask"" prices.  So, if there are hundreds of market makers then there could be hundreds of different bid and ask prices on the same stock.  The prices you see for stocks are what are called the ""best bid and best ask"" prices.  What that means is, you are being shown the highest ""bid"" price (what you can sell your shares for) and the best ""ask"" price (what you can buy those shares for) because that's what is required.  That being said, there are many other market makers on the same stock whose bid prices are lower and ask prices are higher.  Many times there will be a big clump of market makers all at the same bid/ask, or within fractions of a cent of each other, all competing for business.  Trading computers are taught to seek out the best prices and the fastest trade fills they can. The point to this very simplistic lesson is that the market makers set the prices that shares trade at.  They adjust those prices based (among other factors) on how much buying and selling volume they're seeing.  If they see a wave of sell orders coming into the system then they'll start marking down their bid prices.  This keeps them from paying too much for shares they're going to have to find a buyer for eventually, and it can sometimes slow down the pace of selling as investors and automated systems notice the price decline and decide to wait to sell.  Conversely, if market makers see a wave of buy orders coming into the system, they'll start marking their ask prices up to maximize their gains, since they're selling you shares they bought from someone else, presumably at a lower price.  But they typically adjust their prices up or down before they actually fill trades.  (sneaky, eh?) Depending on how much volume there is on the shares of the company you're selling, and depending on whether there are more buyers than sellers at the moment, your share sell order may be filled at market by a market maker with no real consequence to the share's price. If the block is large enough then it's possible it will not all sell to one market maker, or it might not all happen in one transaction or even all at the same price. This is a pretty complex subject, as you can see, and I've cut a LOT of corners and oversimplified much to keep it comprehensible.  But the short answer to your question is -- it depends. Hope this helps. Good luck!" This is rather simple if you understand a trailing limit order but to be sure I am going to explain a limit, trailing limit, and trailing LIT order. I am going to use an example assuming that you already own a stock and want to sell it. Limit Order I place an order to sell 100 PG @ 65.00. This order will only be executed if the bid price of PG is at $65.0000 or greater. Trailing Limit Order I place an order to sell 100 CAT @ 85.25 with a trailing 5%. This order will be executed when CAT drops 5% below the highest point it reaches after you place this order. So if you place this order at 85.25 and the stock drops 5% to $80.9875, your order will be executed. However, if the stock jumps to $98, the order will not be executed until the stock falls to $93.10. The sell point will go up with the stock and will always remain at the specified % or $ amount behind the high point. Trailing Limit If Touched Order I place an order to sell 100 INTC @ 24.75 with a trailing 5% if the stock touches $25.00. Essentially, this is the same as the trailing limit except that it doesn't take effect until the stock first gets $25.00.  I think the page they provide to explain this is confusing because I think they are explaining it from the shorting a stock perspective instead of the selling a stock you want to profit from. I could also be wrong in how I understand it. My advice would be to either call their customer support and ask for a better explanation or what I do in my finances, avoid things I don't understand. "The price of a company's stock at any given moment is established by a ratio of buyers to sellers.  When the sellers outnumber the buyers at a given price, the stock price drops until there are enough people willing to buy the stock to balance the equation again.  When there are more people wanting to purchase a stock at a given price than people willing to sell it, the stock price rises until there are enough sellers to balance things again.  So given this, it's easy to see that a very large fund (or collection of very large funds) buying or selling could drive the price of a stock in one direction or another (because the sheer number of shares they trade can tip the balance one way or another).   What's important to keep in mind though is that the ratio of buyers to sellers at any given moment is determined by ""market sentiment"" and speculation.  People selling a stock think the price is going down, and people buying it think it's going up; and these beliefs are strongly influenced by news coverage and available information relating to the company.  So in the case of your company in the example that would be expected to triple in value in the next year; if everyone agreed that this was correct then the stock would triple almost instantly.  The only reason the stock doesn't reach this value instantly is that the market is split between people thinking this is going to happen and people who think it won't.   Over time, news coverage and new information will cause one side to appear more correct than the other and the balance will shift to drive the price up or down.  All this is to say that YES, large funds and their movements CAN influence a stock's trading value; BUT their movements are based upon the same news, information, analysis and sentiment as the rest of the market.  Meaning that the price of a stock is much more closely tied to news and available information than day to day trading volumes.  In short, buying good companies at good prices is just as ""good"" as it's ever been.   Also keep in mind that the fact that YOU can buy and sell stocks without having a huge impact on price is an ADVANTAGE that you have.  By slipping in or out at the right times in major market movements you can do things that a massive investment fund simply cannot." "In addition to the other answers it's also noteworthy that the stock exchanges themselves adjust the price quotes via their ex-div mechanism.  All limit orders present in the book when the stock goes ex-div will be adjusted by the dividend. Which means you can't even get ""accidentally"" filled in the very unlikely case that everyone forgot to adjust their quotes." You need to use one of each, so a single order wouldn't cover this:  The stop-loss order could be placed to handle triggering a sell market order if the stock trades at $95 or lower.  If you want, you could use a stop-limit order if you have an exit price in mind should the stock price drop to $95 though that requires setting a price for the stop to execute and then another price for the sell order to execute. The limit sell order could be placed to handle triggering a sell if the stock rises above $105. On the bright side, once either is done the other could be canceled as it isn't applicable anymore. A stock buy back reduces the number of stocks available on the open market.  Since stocks are literally a share in ownership a buy back of the stock then when the company repurchases it has the effect of increasing the percent of ownership of the company of each stock. Zynga has a Market Cap of ~1810M so a 200M buy back will increase the ownership value of each stock by ~12%.  This has had the effect of an immediate stock price bump of around 12% which is to be expected as the value becomes the expected post buyback value. However long term gains will require Zynga to turn around their business.  This bump will only be sustainable if they can.  If their business continues to decline then its stock price will continue to slide.  There are some who would rather see Zynga invest that 200m in getting a new product to market to bring revenues up rather than spending precious capital on a plan to temporarily bump a stock that is headed towards the floor.  If on the other hand the revenue is poised to recover and the company has the excess capitol buying back stock low is a great way to get the most back for your shareholders bucks. Can they repurchase at any price and any time? They can write a buy order for any price at any time in the future, though they have some restrictions from the SEC mostly involving disclosures.  But it is up to the sellers to choose to sell at that price.  If they execute the buy back at a rate comparable to market rate then they are more likely to get takers than if they attempt to buy it back at a significant reduction from market price.  So since today(10-25-2012) the it is selling for ~2.30  A buy order for 2.30 is going to get more action than one at 2.00.  Investors will often look at the companies buy back offer for a company in decline(like Zynga has been) as the true value of the company.  If so then a lowball buyback offer could add downward pressure on the stock price.