Purchase same stock twice
how does the trading company know which one I want to sell? It doesn't need to know. You just sell one. From taxation point of view depending on the country / tax jurisdiction, it can be only be FIFO or specific stock. Investors purchase additional shares all the time. Every investor that adds money to their investments does this every paycheck or every month. Investors do this every time they reinvest dividends, interest or capital gains. They also buy and sell shares when they decide to rebalance their portfolio.  Whether you are investing via a broker, mutual fund or ETF the investment company can handle this issue. You do want to know how they want you to specify which shares you want them to sell. The laws in your country may specify a default procedure, or what needs to be done if you want to use another procedure, or if you are allowed to change once you have specified a procedure.
Par value SHOULD mean that they are offering you the options with a strike price (exercise price) that is equivalent to the current valuation of the company.  Note I said SHOULD. As long as you can confirm with HR (or if you're small enough, just ask the CEO) that your grant price is the same as the current valuation of the company's shares, then things are straight.  And while it's very unlikely that someone is doing Something Sneaky, it's always possible.  As a reference, my recent grant letter said:  [Company] (the “Company”) hereby grants you the following Option to   purchase shares of its common stock (“Shares”). The terms and   conditions of this Option are set forth in the Stock Option Agreement   and the [Company] 2013 Stock Incentive Plan (the “Plan”), both of   which are attached to and made a part of this document. Dollar cost averaging can be done in a retirement plan, and can be done for individual stock purchases, as this will increase your returns by reducing your risk, especially if you are buying a particular stock for the first time.   How many time have I purchased a stock, bottom fishing, thinking I was buying at the low, only to find out there was a new low.  Sitting with a thousand shares that are now down $3-$4K.  I have a choice to sell at a loss, hold what I've got or double down.  I usually add more shares if I'm thinking I'll recover, but at that time I'd wished I'd eased into my investment.  That way I would have owned more shares at a smaller cost basis.   Anything can happen in the market, not knowing whether the price will increase or decrease.  In the example above a $3,000 loss is equal to the brokerage cost of about 300 trades, so trading cost should not be a factor.  Now I'm not saying to slowly get into the market and miss the bull, like we're having today with Trump, but get into individual stocks slowly, being fully invested in the market.   Also DCA means you do not buy equal number of shares per period, say monthly, but that you buy with the same amount of money a different number of shares, reducing your total costs.  Let's say you spend $2000 on a stock trading at $10 (200 shares), if the stock rose to $20 you would spend $2000 and buy 100 shares, and if the stock dropped to $5 you would spend $2000 and buy 400 shares, by now having amassed 700 shares for $6,000.  On the other hand and in contrast to DCA had you purchased 200 shares for $2000 at $10/share, then 200 shares for $4000 at $20/share, and finally 200 more shares for $1000 at $5/share, you would have amassed only 600 shares for $7000 investment. Securities (things you can buy on the stock market)  that pay dividends usually pay every quarter (every three months), but some pay every month. (For example: PGF pays dividends each month.) IF you reinvest your dividends back into the stock then you will be compounding your return.  I use the feature at Scottrade to automatically reinvest the dividend each month. Using this feature at Scottrade incurs no commission for the purchases of the stock from the dividend. (saving on commissions and fees is, likely, the most important aspect of investing).  US Treasuries (usually) pay interest twice a year. There is no commission when using Treasury Direct. The typical deal is you can put 10% of your gross pay into the ESPP. The purchase will occur on the last deposit date, usually a 6 month period, at a 15% discount to the market price.  So, the math is something like this: Your return if sold the day it's purchased is not 15%, it's 100/85 or 17.6%. Minor nitpick on my part, I suppose.  Also the return is not a 6 month return, as the weekly or bi-weekly deductions are the average between the oldest (6 mo) and the most recent (uh, zero time, maybe a week.) This is closer to 3 months. The annualized rate is actually pretty meaningless since you don't have 4 opportunities to achieve this return, it's important only if the cash flow hit causes you to borrow to support the ESPP purchases. The risk is whether the stock drops the 15% before you can execute the sell to take advantage of the gain.  Of course the return is gross, you need to net for taxes.  Edit to respond to comment below - When I said meaningless, I meant that you can't take the 17.6%, annualize it to 91.2% per year and think your $1000 will compound to $1912. It's as meaningless as when an investor gets a 10% gain on a stock in one day, and (with 250 trading days per year) decides his $1000 will be worth $2 quadrillion dollars after a year. The 17.6% is significant in that it's available twice per year, for a true 38% return over a year, but if borrowing to help the cash flow, that rate is really over 3 months. Reading the plan documentation, yes, that is what it means.  Each purchase by bank debit, whether one-time or automatic, costs $2 plus $0.06 per share; so if you invested $50, you would get slightly less than $48 in stock as a result (depending on the per-share price). Schedule of Fees Purchases – A one-time $15.00 enrollment fee to establish a new     account for a non-shareholder will be deducted from the     purchase amount. – Dividend reinvestment: The Hershey Company pays the     transaction fee and per share* fee on your behalf. – Each optional cash purchase by one-time online bank     debit will entail a transaction fee of $2.00 plus $0.06 per     share* purchased. – Each optional cash purchase by check will entail a     transaction fee of $5.00 plus $0.06 per share* purchased. – If funds are automatically deducted from your checking or     savings account, the transaction fee is $2.00 plus $0.06     per share* purchased. Funds will be withdrawn on the     10th of each month, or the preceding business day if the     10th is not a business day. – Fees will be deducted from the purchase amount. – Returned check and rejected ACH debit fee is $35.00. "It's impossibly difficult to time the market. Generally speaking, you should buy low and sell high. Picking 25% as an arbitrary ceiling on your gains seems incorrect to me because sometimes you'll want to hold a stock for longer or sell it sooner, and those decisions should be based on your research (or if you need the money), not an arbitrary number. To answer your questions: If the reasons you still bought a stock in the first place are still valid, then you should hold and/or buy more. If something has changed and you can't find a reason to buy more, then consider selling. Keep in mind you'll pay capital gains taxes on anything you sell that is not in a tax-deferred (e.g. retirement) account. No, it does not make sense to do a wash sale where you sell and buy the same stock. Capital gains taxes are one reason. I'm not sure why you would ever want to do this -- what reasons were you considering? You can always sell just some of the shares. See above (and link) regarding wash sales. Buying more of a stock you already own is called ""dollar cost averaging"". It's an effective method when the reasons are right. DCA minimizes variance due to buying or selling a large amount of shares at an arbitrary single-day price and instead spreads the cost or sale basis out over time. All that said, there's nothing wrong with locking in a gain by selling all or some shares of a winner. Buy low, sell high!" For point two.. The norm for buying stock is to just register online with a major broker: Fidelity, Schwab,TD Ameritrade...etc, send them money to fund your purchase, make the stock purchase in your account, and then have a little faith. You could probably get them to physically transfer the stock certificates from them to you, but it is not the norm at all. I would plan on a fee being involved also. The 10$ is for one trade... regardless of if you buy one share or many. So you wouldn't buy 1 share of a five dollar stock as your cost would be absurd. You might buy a hundred shares. "Nobody knows for sure what ""substantially identical"" means because the IRS hasn't officially defined it. Until they do so, it would come down to the decision of an auditor or a tax court. The rule of thumb that I have always heard is if the funds track the same index, they are probably substantially identical. I think most people wouldn't consider any pair of AGG, CMF, and NYF to be substantially identical, so you should be safe with your tax-loss harvesting strategy."