Are there specific dates for companies to declare ordinary dividends? If so, where can I find these dates? If not, why aren't there fixed dates to prevent excessive volatility and speculation about the dividend date and amount?
Like an earnings announcement date, the declaration of a dividend is tied to the company's financials. It happens when the company has completed the task and it isn't necessarily finished by the same date each quarter (or other time period).
There are numerous web sites that provide ex-dividend dates along with record date, pay date and dividend amount. You can find them by googling "Dividend Calendar". Brokers also provide such information.
And no, there isn't excessive volatility due to speculation about the dividend date.
Are there specific dates for companies to declare ordinary dividends?
There is no requirement that they have to be always X days after the end of their quarter, or on the third Wednesday after the end of the quarter. Though if the company is paying a dividend every quarter they might specify the dates of the next dividend votes far in advance, thus giving an approximate date of the dividend.
Remember there is no requirement to pay a dividend. And there is nothing to stop a company from changing the amount or the schedule if the world changes and they want to preserve cash for the future even if they make money this quarter.
why aren't there fixed dates to prevent excessive volatility and speculation about the dividend date and amount?
Most investors don't care about the exact dividend date or amount. If the investment in company X is through a fund, then the dividend is lost in the noise of the other stocks and transactions in the fund.
The subset of individual investors who want the dividend for cash, they care. Those who don't want the cash but will re-invest only care if the investment is not in a retirement account. But they care from a tax perspective.
Traders might care, but because the stock drops with the dividend it generally is a wash. Some may see a way to make money if they see people move in or out of the stock based on the dividend, but that seems to be a rare situation.