Equity prices during currency devaluation — Mexico 1994
Yes, this phenomenon is well documented.  A collapse of an economy's exchange rate is coincidented with a collapse in its equities market.    The recent calamities in Turkey, etc during 2014 had similar results. Inflation is highly correlated to valuations, and a collapse of an exchange rate is highly inflationary, so a collapse of an exchange rate is highly correlated to a collapse in valuations.
Investing in the early 70s would have been fine, trying to pile on the boat after the fact (late 70s, early 80s), those people would lose.    The fluctuations then had largely to do with the collapse of the USSR.  Parallels could certainly be drawn to modern times, but the main thing is that if you invested early, you could ride out the worst of storms without having to worry about a company or a currency becoming worthless overnight. The value of the asset doesn't change just because of the exchange rate change. If a thing (valued in USD) costs USD $1 and USD $1 = CAN $1 (so the thing is also valued CAN $1) today and tomorrow CAN $1 worth USD $0.5 - the thing will continue being worth USD $1. If the thing is valued in CAN $, after the exchange rate change, the thing will be worth USD $2, but will still be valued CAN $1. What you're talking about is price quotes, not value. Price quotes will very quickly reach the value, since any deviation will be used by the traders to make profits on arbitrage. And algo-traders will make it happen much quicker than you can even notice the arbitrage existence. It is different this time. But I think the risk of asset prices rising is almost as equal as them falling. QE caused asset price inflation, but QE was only to calm/support the market. They're probably not going to stuff that QE money back into the central bank for a very long time either. Maybe, they'll just keep rolling over the bonds out to maturity, while relying on deficits to inflate away the assets at the Fed.  https://youtu.be/o8LAUQwv77Q  My bet is the main risks going forward are political risks, and continued modest inflation among things not measured by CPI. "Yes, you're still exposed to currency risk when you purchase the stock on company B's exchange. I'm assuming you're buying the shares on B's stock exchange through an ADR, GDR, or similar instrument. The risk occurs as a result of the process through which the ADR is created. In its simplest form, the process works like this: I'll illustrate this with an example. I've separated the conversion rate into the exchange rate and a generic ""ADR conversion rate"" which includes all other factors the bank takes into account when deciding how many ADR shares to sell. The fact that the units line up is a nice check to make sure the calculation is logically correct. My example starts with these assumptions: I made up the generic ADR conversion rate; it will remain constant throughout this example. This is the simplified version of the calculation of the ADR share price from the European share price:  Let's assume that the euro appreciates against the US dollar, and is now worth 1.4 USD (this is a major appreciation, but it makes a good example):  The currency appreciation alone raised the share price of the ADR, even though the price of the share on the European exchange was unchanged. Now let's look at what happens if the euro appreciates further to 1.5 USD/EUR, but the company's share price on the European exchange falls:  Even though the euro appreciated, the decline in the share price on the European exchange offset the currency risk in this case, leaving the ADR's share price on the US exchange unchanged. Finally, what happens if the euro experiences a major depreciation and the company's share price decreases significantly in the European market? This is a realistic situation that has occurred several times during the European sovereign debt crisis.   Assuming this occurred immediately after the first example, European shareholders in the company experienced a (43.50 - 50) / 50 = -13% return, but American holders of the ADR experienced a (15.95 - 21.5093) / 21.5093 = -25.9% return. The currency shock was the primary cause of this magnified loss.  Another point to keep in mind is that the foreign company itself may be exposed to currency risk if it conducts a lot of business in market with different currencies. Ideally the company has hedged against this, but if you invest in a foreign company through an ADR (or a GDR or another similar instrument), you may take on whatever risk the company hasn't hedged in addition to the currency risk that's present in the ADR/GDR conversion process. Here are a few articles that discuss currency risk specifically in the context of ADR's: (1), (2). Nestle, a Swiss company that is traded on US exchanges through an ADR, even addresses this issue in their FAQ for investors. There are other risks associated with instruments like ADR's and cross-listed companies, but normally arbitrageurs will remove these discontinuities quickly. Especially for cross-listed companies, this should keep the prices of highly liquid securities relatively synchronized." To answer your original question: There is proof out there. Here is a paper from the Federal Reserve Bank of St. Louis that might be worth a read.  It has a lot of references to other publications that might help answer your question(s) about TA.  You can probably read the whole article then research some of the other ones listed there to come up with a conclusion.  Below are some excerpts:  Abstract: This article introduces the subject of technical analysis in the foreign exchange market, with emphasis on its importance for questions of market efficiency.  “Technicians” view their craft, the study of price patterns, as exploiting traders’ psychological regularities.  The literature on technical analysis has established that simple technical trading rules on dollar exchange rates provided 15 years of positive, risk-adjusted returns during the 1970s and 80s before those returns were extinguished.  More recently, more complex and less studied rules have produced    more modest returns for a similar length of time.  Conventional explanations that rely on risk adjustment and/or central bank intervention do not plausibly justify the observed excess returns from following simple technical trading rules.  Psychological biases, however, could contribute to the profitability of these rules. We view the observed pattern of excess returns to technical trading rules as being consistent with an adaptive markets view of the world.    and  The widespread use of technical analysis in foreign exchange (and   other) markets is puzzling because it implies  that either traders are   irrationally making decisions on useless information or that past   prices contain useful  information for trading.  The latter   possibility would contradict the “efficient markets hypothesis,”   which holds that  no trading strategy should be able to generate   unusual profits on publicly available information—such as past    prices—except by bearing unusual risk. And the observed  level of   risk-adjusted profitability measures market  (in)efficiency. Therefore   much research effort has been directed toward determining whether   technical analysis is  indeed profitable or not. One of the earliest   studies, by Fama and Blume (1966), found no evidence that a particular   class of TTRs could earn abnormal profits in the stock market.   However, more recent research by Brock,  Lakonishok and LeBaron (1992)   and Sullivan, Timmermann an d White (1999) has provided contrary   evidence. And  many studies of the foreign exchange market have found   evidence that TTRs can generate persistent profits (Poole  6  (1967),   Dooley and Shafer (1984), Sweeney (1986), Levich and Thomas (1993),   Neely, Weller and Dittmar (1997),  Gençay (1999), Lee, Gleason and   Mathur (2001) and Martin (2001)). "Debt is nominal, which means when inflation happens, the value of the money owed goes down.  This is great for the borrower and bad for the lender. ""Investing"" can mean a lot of different things.  Frequently it is used to describe buying common stock, which is an ownership claim on a company.  A company is not a nominally fixed asset, by which I mean if there was a bunch of inflation and nothing else happened (i.e., the inflation was not the cause or result of some other economic change) then the nominal value of the company will go up along with the prices of other things. Based on the above, I'd say you are incorrect to treat debt and investment returns the same way with respect to inflation.  When we say equity returns 9%, we mean it returns a real 7% plus 2% inflation or whatever.  If the rate of inflation increased to 10% and nothing else happened in the economy, the same equity would be expected to return 17%.  In fact, the company's (nominally fixed) debts would be worth less, increasing the real value of the company at the expense of their debt-holders. On the other hand, if we entered a period of high inflation, your debt liability would go way down and you would have benefited greatly from borrowing and investing at the same time.   If you are expecting inflation in the abstract sense, then borrowing and investing in common stock is a great idea. Inflation is frequently the result (or cause) of a period of economic trouble, so please be aware that the above makes sense if we treat inflation as the only thing that changed.  If inflation came about because OPEC makes oil crazy expensive, millennials just stop working, all of our factories got bombed to hades, or trade wars have shut down international commerce, then the value of stocks would most definitely be affected.  In that case it's not really ""inflation"" that affected the stock returns, though." One place you might consider looking for answers is in case studies from Harvard Business School.  When I was working an MBA, we studied the default of Argentina as part of our economics coursework. Other sources for your consideration might include: "I found an answer by Peter Selinger, in two articles, Tutorial on multiple currency accounting (June 2005, Jan 2011) and the accompanying Multiple currency accounting in GnuCash (June 2005, Feb 2007). Selinger embraces the currency neutrality I'm after. His method uses ""[a]n account that is denominated as a difference of multiple currencies... known as a currency trading account."" Currency trading accounts show the gain or loss based on exchange rates at any moment.  Apparently GnuCash 2.3.9 added support for multi-currency accounting. I haven't tried this myself. This feature is not enabled by default, and must be turned on explicity. To do so, check ""Use Trading Accounts"" under File -> Properties -> Accounts. This must be done on a per-file basis. Thanks to Mike Alexander, who implemented this feature in 2007, and worked for over 3 years to convince the GnuCash developers to include it. Older versions of GnuCash, such as 1.8.11, apparently had a feature called ""Currency Trading Accounts"", but they behaved differently than Selinger's method." Anything related to the central bank will have a large impact, as they are the ones who determine interest rates, and interest rates have a big effect on currency flows.  GDP is also important, as when there is an economic slowdown it may result in the central bank reducing rates to boost economic activity. The opposite is also true, large increases in GDP may mean that an interest rate hike might be needed. Inflation data is also very important. Again, large changes in inflation either way may push the central bank towards changing rates. This data typically is in the form of CPI Note that each central bank is different. They all have specific mandates and specific pieces of economic data that they place emphasis on. The Federal Reserve as of late has closely been watching inflation data, especially wage inflation data, and employment. Significant deviations in these data points from whats expected by investors can greatly move the market. However, these specific factors are a little less important for, say, Mexico, which is mostly concerned with headline inflation. Read the statements issued by the central banks to find out whats important to them. Central banks also issue expectations for things like growth, CPI, etc. If these expectations are not met, it may result in a policy change, or at least talk of a policy change, at the next meeting of the central bank. Anticipating these policy changes and trading accordingly is one strategy to be a profitable forex trader Also, there are several forex news calendars online that indicate what is likely to be high impact news. These can be helpful starting out. If one of the EURO countries goes bankrupt, then it will destablise the entire financial industry. IE there would be many financial institutions [Banks, Credit Union, Pension Funds, Insurance Funds, Corporates] that are holding EURO Investments in that country will loose their money and this will have a cascading impact ... similar and much bigger than US Sub-prime crisis of 2008. So if your money is in EURO and you are staying in EURO countires, the inflation will mean your money is of less value ... If you are holding USD and staying in EURO and country goes bankrupt then chances are that it will loose value with USD and hence you can convert them to EURO and spend more EUROs to buy the same items ... "The first thing to realize is that the type of chart you saw is not appropriate for long-term comparisons.  The vertical axis uses a linear scale, where each unit occupies the same amount of space.  This is visually misleading because the relevant information at any point in the chart is ""how much is the value going up or down?"" and ""how much"" change depends on how much the value of the investment is at that moment.  For example, if you buy something at $10 and the price changes $1, that is significant, 10%.  If you buy something at $1000 and the price changes $1, that is not so significant, only 0.1%.  The problem in that chart is that 100 Dow points occupy the same space whether the Dow is at 870 or 10800. To get a better feel for the volatility, you should use a log (logarithmic) scale.  Google has an option for this.  Using it shows:   In this chart you can see that the volatility appears much less extreme in recent years.  True, the 2006-2009 change is the largest drop, and there might be slightly higher volatility generally, but it is not nearly as extreme-looking.  The drops in 1974 and 1987 can be seen to be significant." "There are basically two different markets for ADRs and ordinary shares. 1) The American market, 2) the ""local"" market. The following is not true for most stocks in ""developed"" markets. But it is often true that the American market (for ADRs) is far more liquid than the local market for ordinary shares of a developing country. For instance, there was a time when the ADRs of Telmex (Telefonos of Mexico) was the fifth most traded stock in the world, after Exxon (before its merger with Mobil), IBM, Microsoft, and A T&T, meaning that it was easy to trade with low fees on the NYSE. It was much harder and slower to buy the local shares of Telmex in Mexico, on the Mexican exchange. Also, the accompanying currency transactions were harder to execute with the ord, because you have to settle in local currency and pay an FX commission. With the ADR, the exchange rate is ""built"" into the (dollar) price, and you settle in dollars." If you make money in currency speculation (as in your example), that is a capital gain. A more complicated example is if you were to buy and then sell stocks on the mexican stock exchange.  Your capital gain (or loss) would be the difference in value in US dollars of your stocks accounting for varying exchange rates.  It's possible for the stocks to go down and for you to still have a capital gain, and vice versa. "You are violating the Uncovered Interest Rate Parity.  If Country A has interest rate of 4% and Country B has interest rate of 1%, Country B's expected exchange rate must appreciate by 3% compared to spot. The ""persistent pressure to further depreciate"" doesn't magically occur by decree of the supreme leader. If there is room for risk free profit, the entire Country B would deposit their money at Country A, since Country A has higher interest rate and ""appreciates"" as you said. The entire Country A will also borrow their money at Country B.  The exception is Capital Control. Certain people are given the opportunity to get the risk free profit, and the others are prohibited from making those transactions, making UIP to not hold." The measure of change of value of a currency in relation to itself is inflation (or deflation).