LONDON -- I always keep an eye out for directors buying shares in their own companies. It's one useful way of generating investment ideas for further research.

I'm going to tell you about five companies where directors have recently been opening their wallets to make major share purchases. Two of the companies are FTSE 100 blue chips: Admiral (LSE: ADM.L) and Barclays (LSE: BARC.L). Two are midcaps: Chemring Group (LSE: CHG.L) and Fidessa Group (LSE: FDSA.L). The final company is an intriguing small cap called Hydrodec Group (LSE: HYR.L).

Barclays
In August, Barclays announced the appointment of City veteran Sir David Walker as its new chairman in the wake of the LIBOR scandal. Sir David, who had led the inquiry into corporate governance in the banking sector after the financial crisis, bought his first Barclays shares in September: 54,000 pounds' worth at an average price of about 215 pence a share. The chairman added to his stake at the beginning of this month, spending a further 115,000 pounds at just more than 230 pence a share.

Sir David's investment is already showing a healthy gain, with the shares currently trading at 252 pence. Despite the rise, Barclays is still on a forecast price-to-earnings ratio of less than eight for the current year, falling to seven for 2013.

Admiral
Back in September, the wife of the chief executive of car insurance group Admiral went on a 2 million pound buying spree, bagging shares in the company at an average price of a little more than 1,100 pence.

This month there's been heavy buying by chief operating officer David Stevens and a nonexecutive director, John Sussens. The COO dropped almost 1 million pounds at 1,022 pence a share, while the nonexec bought more than 200,000 pounds' worth of shares in two lots at 1,064 pence and 1,081 pence.

Admiral's shares are currently trading at 1,085 pence, giving an unexciting forecast P/E of 12 for the current year, but a whopping forecast dividend yield of 8%. Admiral has an attractive dividend policy for income investors, as it produces a big distribution of cash to shareholders. With the yield standing at its current level, you can see why the directors have been keen to increase their own shareholdings!

Chemring
Midcap Chemring has been profit-warning prone of late, but directors at the defense group have recently shown their faith in the company's future by digging deep into their pockets to buy shares at a current lowly level.

Chairman Peter Hickson and new CEO Mark Papworth each bought more than 100,000 pounds of shares last week at about 225 pence per share. They were joined by nonexecutive Vanda Murray, who made a small, ISA-sized purchase. The company will be giving an update on trading this coming Tuesday ahead of full-year results in January.

As things stand, at a share price of 229 pence, the forecast P/E for this year is six, with a flat dividend expected, giving a yield approaching 7%. The directors are clearly looking beyond the near-term challenges of defense budget constraints in NATO markets.

Fidessa
Fidessa, an FTSE 250 firm with a suite of financial software products and services, has been described by shrewd fund manager Nick Train as "an exceptional company by all criteria and certainly one of the U.K.'s handful of global technology leaders."

Revenue and earnings growth at Fidessa have slowed over the last year or two amid the ongoing travails of the financial sector, but two directors were keen to buy shares at 1,274 pence last week. Chairman John Hamer bought more than 30,000 pounds' worth, and CEO Chris Aspinwall spent about 133,000 pounds.

The directors paid 16.5 times current-year forecast earnings, but the shares have since risen to 1,424 pence, and the P/E to 18.5. With growth at the business expected to be fairly stagnant over the next couple of years, this is perhaps one that investors could wait on for renewed weakness in the share price.

Hydrodec
I'd imagine few readers have come across Hydrodec before. This clean-tech industrial oil-rerefining group is listed on AIM and has a market capitalization of little more than 50 million pounds. Revenue has grown sixfold over the past five years, but the company has yet to make a profit.

On the face of it, that may not sound too promising. However, Hydrodec has pulled off something of a profile-raising coup with the recent appointment of a new chairman: Lord Moynihan. The energy minister from 1990 to 1992, Lord Moynihan recently stood down as chairman of the British Olympic Association after a seven-year term during which he oversaw Team GB's successes in the Beijing and London games.

Since the announcement of Lord Moynihan's appointment as the chairman of Hydrodec in October, he and his fellow directors have been buying shares with abandon:

Date of Purchase

Buyer

Share Price (pence)

Value (pounds)

Nov. 2

Lord Moynihan

12.5

98,750

Oct. 31

Chris Ellis (chief financial officer)

10.75

48,144

Oct. 30

Andrew Black (nonexecutive director)

9.9

494,750

Oct. 24

Lord Moynihan

9

198,929

A fairly impressive show of faith from the directors of a loss-making company, I think you'll agree! The shares are currently trading at 11.25 pence.

Contrarian
The five companies in this article all face challenges of various sorts in the short term, but the directors have backed their businesses against the market's present valuation of them.

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