Is capturing a loss a unique opportunity?
I agree, one should not let the tax tail wag the investing dog.  The only question should be whether he'd buy the stock at today's price. If he wishes to own it long term, he keeps it. To take the loss this year, he'd have to sell soon, and can't buy it back for 30 days. If, for whatever reason, the stock comes back a bit, he's going to buy in higher.  To be clear, the story changes for ETFs or mutual funds. You can buy a fund to replace one you're selling, capture the loss, and easily not run afoul of wash sale rules.
There are two unique identifiers for a bank account: SWIFT code + bank internal identifier, or IBAN code. IBAN is mostly used within European banking system, and the whole code provides a direct and unique identification of the account. SWIFT is an international network where each bank/bank branch has its own address, and account number is a metadata added to the message for the receiving bank to handle. Usually the name of the recipient and additional information are required when wiring money through the SWIFT network, to match the records and make sure there's no mistake. Account numbers don't have to be unique, not even within the same bank. There's always something else in addition to uniquely identify them. I believe WMT already uses most grocery items as loss leaders, so I wouldn't be surprised if Amazon follows a similar structure. Amazon already forgoes profits on many categories (especially new markets) in favour of capturing a large market share. So, expect a big price squeeze on existing brick &amp; mortar joints. The risk situation of the put option is the same whether you own the stock or not.  You risk $5 and stand to gain 0 to $250 in the period before expiration (say $50 if the stock reaches $200 and you sell).   Holding the stock or not changes nothing about that.  What is different is the consideration as to whether or not to buy a put when you own the stock.  Without an option, you are holding a $250 asset (the stock), and risking that money.  Should you sell and miss opportunity for say $300? Or hold and risk loss of say $50 of your $250?  So you have $250 at risk, but can lock in a sale price of $245 for say a month by buying a put, giving you opportunity for the $300 price in that month.  You're turning a risk of losing $250 (or maybe only $50 more realistically) into a risk of losing only $5 (versus the price your stock would get today). Welcome to newborn photography. We have many types of photographers. We capture small children photos. Our photography is very smart and our picture quality is the best. If you are going to welcome a newborn baby in your house and willing to capture all the precious moments, then you must hire and approach the best minneapolis newborn photographer to avail their services. Many customers walk our doors because our camera picture quality is better and clearer. We have many years of experience in newborn photography. When a child is about two to four weeks, we are always ready to capture him/her. "If you really believe in the particular stocks, then don't worry about their daily price.  Overall if the company is sound, and presumably paying a dividend, then you're in it for the long haul. Notwithstanding that, it is reasonable to look for a way out.  The two you describe are quite different in their specifics. Selling sounds like the simpler of the two, but the trigger event, and if it is automatic or ""manual"" matters.  If you are happy to put in a sell order at some time in the future, then just go ahead with that. Many brokers can place a STOP order, that will trigger on a certain price threshold being hit.  Do note, however, that by default this would place a market order, and depending on the price that breaks through, in the event of a flash crash, depending on how fast the brokers systems were, you could find yourself selling quite cheaply. A STOP LIMIT order will place a limit order at a triggered price.  This would limit your overall downside loss, but you might not sell at all if the market is really running away. Options are another reasonable way to deal with the situation, sort of like insurance.  In this case you would likely buy a PUT, which would give you the right, but not the obligation to sell the stock at the price the that was specified in the option.  In this case, no matter what, you are out the price of the option itself (hence my allusion to insurance), but if the event never happens then that was the price you paid to have that peace of mind. I cannot recommend a specific course of action, but hopefully that fleshed out the options you have." "I can address what it means to ""pick off"" all those trades... As quantycuenta & littleadv have said, it is absolutely true that professionals ""prey"" on less-sophisticated market participants. They aren't in the market for charity's sake.  If you're not familiar with the definition of the word ""arbitrage"", look it up.  One possible strategy that can be employed with HFT machinery in order to arbitrage successfully in the stock market is to 'intercept' orders that are placed on various exchanges. In order to do this, an HFT organization watches all the transactions at once to find opportunities to buy low and sell high.  A good explanation of it is described here in this NY Times article; I'll paraphrase what that article lays out.  Stocks are traded through multiple exchanges The first key point to understand is that stocks listed on one exchange (i.e. the NYSE) can be sold on multiple exchanges. That's where the actual ""I would like to sell 100 shares of Ford stock"" is matched with ""I would like to buy 100 shares of Ford stock."" There are multiple clearinghouses on the various exchanges. Your order gets presented to one exchange at a Time An ideal market maker would like to look at the order books for a given stock, say Ford, and see that in exchange A there's a sell order for 100 shares of F at $15.85, and in exchange B there's a buy order for 100 shares of F at $15.90.  Arbitrage Market maker buys from A, sells in B, and pockets $0.05 * 100... $5. It's not much, but it was relatively risk free. Also, scale this up to the scale of the US' multiple stock exchanges, and there are lots of opportunities to make $5 every second.  Computers are (of course) faster than people To tie it in completely with your question about 'picking off trades', HFT rigs can be set up and programmed to go faster than an average retail investor's order.  Let's say you execute the trade to buy 100 shares @ $15.85 as a retail investor. The HFT rigs see your order starting to make the rounds of the different exchanges that your brokerage works through, and go out in front in a matter of milliseconds, finding the orders that are less than $15.85 and less than or equal to 100 shares. They execute a transaction, buy them up, sell to you, and pocket the difference.  You have been ""picked off"".  It's admittedly not the only way to use HFT equipment to make money, but it's definitely one way to do it." I'm of the opinion that speculating is for young people like you, because they can afford to lose it all. Avoiding losses becomes necessary once you have to sustain a family, and manage a somewhat large retirement funds. Even if you lose all your money when speculating, you'll probably be better off later, because you make less costly mistakes once you have larger amounts of money. "It sounds like this is an entirely unsettled question, unfortunately.  In the examples you provide, I think it is safe to say that none of those are 'substantially identical'; a small overlap or no overlap certainly should not be considered such by a reasonable interpretation of the rule. This article on Kitces goes into some detail on the topic.  A few specifics. First, Former publication 564 explains: Ordinarily, shares issued by one mutual fund are not considered to be substantially identical to shares issued by another mutual fund. Of course, what ""ordinarily"" means is unspecified (and this is no longer a current publication, so, who knows). The Kitces article goes on to explain that the IRS hasn't really gone after wash sales for mutual funds: Over the years, the IRS has not pursued wash sale abuses against mutual funds, perhaps because it just wasn’t very feasible to crack down on them, or perhaps because it just wasn’t perceived as that big of an abuse. After all, while the rules might allow you to loss-harvest a particular stock you couldn’t have otherwise, it also limits you from harvesting ANY losses if the overall fund is up in the aggregate, since losses on individual stocks can’t pass through to the mutual fund shareholders. But then goes to explain about ETFs being very different: sell SPY, buy IVV or VTI, and you're basically buying/selling the identical thing (99% or so correlation in stocks owned).   The recommendation by the article is to look at the correlation in owned stocks, and stay away from things over 95%; that seems reasonable in my book as well. Ultimately, there will no doubt be a large number of “grey” and murky situations, but I suspect that until the IRS provides better guidance (or Congress rewrites/updates the wash sale rules altogether!), in the near term the easiest “red flag” warning is simply to look at the correlation between the original investment being loss-harvested, and the replacement security; at correlations above 0.95, and especially at 0.99+, it’s difficult to argue that the securities are not ”substantially identical” to each other in performance. Basically - use common sense, and don't do anything you think would be hard to defend in an audit, but otherwise you should be okay."