Risk to Reward Ratio Calculation
If you plan to take profit at $1.00 then your profit will be $40. Then, if you set your stop at $0.88 then your loss if you get stopped will be $20.  So your Reward : Risk = 2:1.  Note, that this does not take into account brokerage in and out and any slippage from the price gapping past your stop loss.
Having just purchased an upcoming Samsung phone using their 0% interest I can tell you that the justification is to give you credit. I have the same with Best Buy which is 0% for a specific initial purchase. The bank (in the Samsung case is TD Bank) establishes a rotating credit line for you. The APR after is well established at the very high side of 29.99%. Nobody in their right mind should want to pay that much interest on any purchase. My last car purchase was below 3% APR. Additionally the introductory rate will still calculate their 29.99% interest as if it existed since the first day of credit and will be applied to your balance should you ever be late on any single payment. At that time the interest is factored in as if it were always there and payments are adjusted accordingly. You see, the bank wants you to pay their high interest rate. So they entice you with the 0% and hope you either finance more on that credit line (exempt from the promotional rate) or miss a payment and they can hit you with a whammy. Specifically the question asks how this offer benefits Samsung. To answer that portion; it ensures a sale at full retail price of the phone. Samsung is just an agent between you and the bank. The bank takes on the risk for a potential high reward. "The mutual fund is legally its own company that you're investing in, with its own expenses. Mutual fund expense ratios are a calculated value, not a promise that you'll pay a certain percentage on a particular day. That is to say, at the end of their fiscal year, a fund will total up how much it spent on administration and divide it by the total assets under management to calculate what the expense ratio is for that year, and publish it in the annual report. But you can't just ""pay the fee"" for any given year. In a ""regular"" account, you certainly could look at what expenses were paid for each fund by multiplying the expense ratio by your investment, and use it in some way to figure out how much additional you want to contribute to ""make it whole"" again. But it makes about as much sense as trying to pay the commission for buying a single stock out of one checking account while paying for the share price out of another. It may help you in some sort of mental accounting of expenses, but since it's all your money, and the expenses are all part of what you're paying to be able to invest, it's not really doing much good since money is fungible. In a retirement account with contribution limits, it still doesn't really make sense, since any contribution from outside funds to try to pay for expense ratios would be counted as contributions like any other. Again, I guess it could somehow help you account for how much money you wanted to contribute in a year, but I'm not really sure it would help you much. Some funds or brokerages do have non-expense-ratio-based fees, and in some cases you can pay for those from outside the account. And there are a couple cases where for a retirement account this lets you keep your contributions invested while paying for fees from outside funds. This may be the kind of thing that your coworker was referring to, though it's hard to tell exactly from your description. Usually it's best just to have investments with as low fees as possible regardless, since they're one of the biggest drags on returns, and I'd be very wary of any brokerage-based fees when there are very cheap and free mutual fund brokerages out there." "One key point that other answers haven't covered is that many credit cards have a provision where if you pay it off every month, you get a grace period on the interest.  Interest doesn't accrue at all unless you rollover a non-zero balance.  But if you do, you pay interest on the average balance, not the rolled-over balance, for the entire month. You have to ask yourself what you are trying to accomplish with your credit history? Are you trying to maximize your ""buying power"" (really, leverage)?  Or are you trying to make sure that you get the best terms on a moderately sized loan (house mortgage, car note)? As JohnFx and losthorse already noted, it's in the banker's best interest to maximize the profit they make off of you.  Of course, that is not in your best interest. Keeping a credit card balance from month to month definitely feeds the greedy nature of the financing beast.  And makes them willing to take more risks, because the returns are also higher.  But those returns cost you. If you are planning to get sensible loans in the future, that you can comfortably afford, you won't need a maxed credit score.  You won't get the largest loan amounts, but because you are doing the sensible thing and making a large down payment, the risk is also very low and you'll find lenders willing to give you a low interest rate.  Because even though the reward is lower than the compulsive purchaser who pays an order of magnitude more in financing fees, the return/risk ratio is still very favorable to the bank. Don't play the game that maximizes their return.  That happens when you have a loan of maximum size, high interest rate, and struggle to make payments, end up missing a couple and paying late fees, or request forbearance which compounds the interest. Play to minimize risk." If you have 100% of your money in one security that is inherently more risky than splitting your money 50/50 between two securities, regardless of the purported riskiness of the two securities. The calculations people use to justify their particular breed of diversification may carry some assumptions related risk/reward calculations.  But these particular justifications don't change the fact that spreading your money across different assets protects your money from value variances of the individual assets.  Splitting your $100 between Apple and Microsoft stock is probably less valuable (less well diversified) than splitting your money between Apple and Whole Foods stock but either way you're carrying less risk than putting all $100 in to Apple stock regardless of the assumed rates of return for any of these companies stock specifically. Edit: I'm sure the downvotes are because I didn't make a big deal about correlation and measuring correlation and standard deviations of returns and detailed portfolio theory.  Measuring efficacy and justifying your particular allocations (that generally uses data from the past to project the future) is all well and good.  Fact of the matter is, if you have 100% of your money in stock that's more stock risk than 25% in cash, 25% in bonds and 50% in stock would be because now you're in different asset classes.  You can measure to your hearts delight the effects of splitting your money between different specific companies, or different industries, or different market capitalizations, or different countries or different fund managers or different whatever-metrics and doing any of those things will reduce your exposure to those specific allocations.   It may be worth pointing out that currently the hot recommendation is a plain vanilla market tracking S&P 500 index fund (that just buys some of each of the 500 largest US companies without any consideration given to risk correlation) over standard deviation calculating actively managed funds.  If you ask me that speaks volumes of the true efficacy of hyper analyzing the purported correlations of various securities. If you mean the internal rate of return, then the quarterly rate of return which would make the net present value of these cash flows to be zero is 8.0535% (found by goal seek in Excel), or an equivalent compound annual rate of 36.3186% p.a. The net present value of the cash flows is: 10,000 + 4,000/(1+r) - 2,000/(1+r)^2 - 15,125/(1+r)^3, where r is the quarterly rate. If instead you mean Modified Dietz return, then the net gain over the period is: End value - start value - net flow = 15,125 - 10,000 - (4,000 - 2,000) = 3,125 The weighted average capital invested over the period is: 1 x 10,000 + 2/3 x 4,000 - 1/3 x 2,000 = 12,000 so the Modified Dietz return is 3,125 / 12,000 = 26.0417%, or 1.260417^(1/3)-1 = 8.0201% per quarter, or an equivalent compound annual rate of 1.260417^(4/3)-1 = 36.1504%. You are using an inappropriate formula, because we know for a fact that the flows take place at the beginning/end of the period. Instead, you should be combining the returns for the quarters (which have in fact been provided in the question). To calculate this, first calculate the growth factor over each quarter, then  link them geometrically to get the overall growth factor. Subtracting 1 gives you the overall return for the 3-quarter period. Then convert the result to a quarterly rate of return. Growth factor in 2012 Q4 is 11,000/10,000 = 1.1 Growth factor in 2013 Q1 is 15,750/15,000 = 1.05 Growth factor in 2013 Q2 is 15,125/13,750 = 1.1 Overall growth factor is 1.1 x 1.05 x 1.1 = 1.2705 Return for the whole period is 27.05% Quarterly rate of return is 1.2705^(1/3)-1 = 8.3074% Equivalent annual rate of return is 1.2705^(4/3)-1 = 37.6046% ========= I'd recommend you to refer to Wikipedia. "I would change that statement to ""very few people can CONSISTENTLY beat the market "". Successful strategies will get piled into and reduce returns. Markets will pick up inefficiencies, but at the same time they do exists. Tons of interesting reading especially in regards to value. Is there a risk premium that we don't know for value? Or is it a market behavior thing?" There are many ways to calculate the return, and every way will give you a different results in terms of a percentage-value. One way to always get something meaningful - count the cash. You had 977 (+ 31) and in the end you have 1.370, which means you have earned 363 dollars. But what is your return in terms of percentage? One way to look at it, is by pretending that it is a fund in which you invest 1 dollar. What is the fund worth in the beginning and in the end? The tricky part in your example is, you injected new capital into the equation. Initially you invested 977 dollars which later, in the second period became worth 1.473. You then sold off 200 shares for 950 dollars. Remember your portfolio is still worth 1.473, split between 950 in cash and 523 in Shares. So far so good - still easy to calculate return (1.473 / 977 -1 = 50.8% return). Now you buy share for 981 dollars, but you only had 950 in cash? We now need to consider 2 scenarios. Either you (or someone else) injected 31 dollars into the fund - or you actually had the 31 dollars in the fund to begin with. If you already had the cash in the fund to begin with, your initial investment is 1.008 and not 977 (977 in shares and 31 in cash). In the end the value of the fund is 1.370, which means your return is 1.370 / 1.007 = 36%. Consider if the 31 dollars was paid in to the fund by someone other than you. You will then need to recalculate how much you each own of the fund. Just before the injection, the fund was worth 950 in cash and 387 in stock (310 - 200 = 110 x 3.54) = 1.339 dollars - then 31 dollars are injected, bringing the value of the fund up to 1.370. The ownership of the fund is split with 1.339 / 1.370 = 97.8% of the value for the old capital and 2.2% for the new capital. If the value of the fund was to change from here, you could calculate the return for each investor individually by applying their share of the funds value respective to their investment. Because the value of the fund has not changed since the last period (bullet 3), the return on the original investment is (977 / 1.339 - 1 = 37.2%) and the return on the new capital is (31 / 31 = 0%). If you (and not someone else) injected the 31 dollar into the fund, you will need to calculate the weight of each share of capital in each period and get the average return for each period to get to a total return. In this specific case you will still get 37.2% return - but it gets even more comlex for each time you inject new capital. Dummy example to explain this. Suppose your portfolio contained just two securities; a thirty year US government bond and a Tesla stock. Both of those position are currently valued at $1mm. The Tesla position however is very volatile with its daily volatility being about 5% (based on the standard deviation of its daily return) whole there bond's daily volatility is 1%. Then the Tesla position is 5/6 of your risk while being only 1/2 of the portfolio.   Now if in month the Tesla stock tanks to half is values then. Then it's risk is half as much as before and so it's total contribution to risk has gone down.