How quickly can you double your money with an investment in shares? We all hope to get a few quick multi-baggers in our investing careers, but the great bulk of the profit is made by the slow and steady accumulation and reinvestment of rising annual earnings.

Extra boost

Sometimes we can get an extra boost when we see share prices unfairly depressed, as has happened with BAE Systems (LSE: BA) in recent years. Back in 2011, with recession surrounding us and defence prospects looking a bit grim, BAE shares plunged as low as 253p and ended the year on a P/E of only a little over six — even for a depressed sector, that seemed ludicrously cheap.

Between that low point and today, BAE shares have soared by 90% to 480p, and dividends over the period would have made that up to around 125% — way better than a doubling, in just a bit over four and a half years.

How quickly might BAE shares double again? Let’s suppose the forecast return to EPS growth of 6% in 2017 is sustained and the dividend continues to yield around 4.5%, and also assume that the shares return to P/E in line with the FTSE 100 long-term average of around 14…

That’s perhaps a bit optimistic, but including dividends it suggests BAE shares could double again by the end of 2020 — that is, in just over another four years.

Oily double?

Speaking of depressed industries, we have the slump in BP (LSE: BP) shares. Well, I say slump, but BP shares have actually only fallen by 30% since mid-2014, to 364p, and two years of very high dividends would have reduced your loss to only around 15% — and if that’s the biggest share price disaster we ever face, we won’t be doing too badly at all.

But with Brent Crude now edging ever closer to $50 a barrel — it’s at $49.33 as I write — what does the future hold for BP shares? Forecasts suggest a a P/E of only around 13.5 for 2017, and they’ve been based largely on the low oil prices of the past couple of months. But analysts are already upping their forecasts in the light of the strengthening oil price, and are putting out a pretty strong Buy rating on BP shares.

The prospects for BP really depend on the future of the oil price and where it will stabilize. BP apparently believes that it will get back to $100 again in the future as demand rises, although in the short to medium term that would seem optimistic. But a number of pundits are suggesting around $75 in the medium term, and that could easily double BP’s earnings per share — and, assuming the P/E remains the same, that would double the share price.

Quad-play telecom

Now that BT Group (LSE: BT.A) is back in the mobile business through its acquisition of EE, and is doing nicely in the content-delivery stakes, it has to be the quad-play operator to beat. Over five years, BT shares have put in the best performance of the three here today, gaining 123% on share price alone with dividends taking that up to around 150%.

Even after that, and with dividends expected to yield 4%, BT shares are on a forward P/E for the year ending march 2018 of just 13.5. That’s likely due to a 7% fall in earnings on the cards for the current year, after 2015-16 saw EPS growth slow to 5%.

But I think using that as a valuation misses one key fact — BT has been in a high capital expenditure mode in recent years, and that’s set to drop as it goes about integrating its acquisitions and hopefully enjoying future cost savings as a result.

How long it will take for BT shares to double again is anybody’s guess, but I’d say there’s at least an evens chance it’ll happen in the next five years.

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Alan Oscroft has no position in any shares mentioned. The Motley Fool UK has recommended BP. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.