LONDON -- If you want to be eligible for a dividend payment, or if you're watching for possible share price falls, keeping up with ex-dividend dates can prove beneficial. So long as you hold the shares up to and including that day, you'll get your money.

We have a small number of companies from the FTSE 100 and FTSE 250 reaching their crucial dates next week. Here are three that will go ex-dividend next Wednesday, May 29.

AMEC, the provider of engineering and other services to a number of sectors including the oil and gas sector, released good-looking full-year results in February. Reported revenue gained 28% to £4.2 billion, with underlying revenue up 21%. And with earnings per share up 14% and operating cash flow up 16%, the firm was able to lift its full-year dividend by 20% to 36.5 pence per share.

The payment comprises an earlier interim dividend of 11.7 pence per share, with a final contribution of 24.8 pence -- and the date for that final portion is May 29. AMEC's dividend yield is not especially high, at 3.5% on the current share price of 1,056 pence, but it is well covered, and the firm has been making reliably increasing annual payouts.

Spectris (LSE:SXS)
Electronic instruments and controls specialist Spectris proposed a final dividend of 25.5 pence per share at the time of its annual results in February, taking its total payment for the year to 39 pence per share for a rise of 16%. On the latest share price of 2,109 pence, that provides a yield of 1.8% -- not massively high, but the dividend has been rising nicely over the past few years.

This year's dividend was made possible by an 11% rise in sales to £1.23 billion, adjusted pre-tax profit up 13% to £217 million, and an 11% boost in adjusted EPS to 137.5 pence.

Marston's (LSE:MARS)
The last of our trio this week is Marston's, the pub manager and brewer, which will go ex-dividend with respect to an interim payment of 2.3 pence per share. Announced with interim results last week, that's a 4.5% increase on the first-half payout a year ago and comes despite underlying pre-tax profit falling 18% to £27.6 million and underlying EPS dropping 19% to 3.8 pence per share. Still, the firm did express confidence in hitting its full-year targets.

If the same increase is repeated for the final dividend, we'd see a payment of near 6.4 pence per share for a yield of 4.2% on the latest 154 pence price -- and that's with the share price having soared by 55% over the past 12 months.

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