Shares in advertising group WPP (LSE: WPP) hit a record high after the group published its interim results this morning, but commodity firm Glencore (LSE: GLEN) sank after its results were announced.

Let’s take a closer look at this morning’s news, and ask whether either company deserves a buy rating at the moment.

“Considerable pressure in the system”

Reported revenue rose by 11.9% to £6.54bn at advertising group WPP during the first half of the year. Adjusted pre-tax profit was £690m, 15.8% higher than last year, while adjusted earnings per share rose by 16.7% to 39.1p.

Shareholders will see their interim dividend payout rise by 22.9% to 19.55p per share this year, as a result of WPP’s new policy of paying out 50% of earnings as dividends.

Today’s results show little evidence of what WPP boss Sir Martin Sorrell describes as “considerable pressure in the [economic] system.” In his comments this morning, Sir Martin said that WPP’s strong performance had been delivered in spite of slower global GDP growth and a “cautious” outlook from clients.

WPP’s sales and profits were given a boost by exchange rates during the first half, but today’s figures are still impressive. Investors certainly appear to be pleased. WPP shares have risen by 5.6% to a record high of more than 1,840p this morning.

Today’s gains mean that WPP’s share price has risen by 41% over the last year, making it one of the best-performing stocks in the FTSE 100. The firm’s shares now trade on a 2016 forecast P/E of 17 and offer a prospective yield of about 3%. Is it too late to buy?

WPP expects second-half growth to be slower. The firm’s latest guidance is for like-for-like revenue growth of “well over 3%” this year, together with a 0.3% increase in profit margins.

Its track record of expanding through organic growth and acquisitions is impressive. I believe the firm’s shares could still deliver long-term gains from current levels, but I intend to wait for a period of weakness before adding any more to my own holding.

Should you buy the dips?

Shares in commodity trading and mining group Glencore fell by 4% this morning, after the company said that adjusted operating profit had fallen by 38% to $875m during the first half of the year.

Falling profits may partly be a side effect of the $4bn-$5bn of assets sales Glencore has inked so far this year. These helped the group to reduce net debt by 9% to $23.6bn during the first half.

Glencore said this morning that it remains confident of hitting its 2016 target for net debt of $16.5bn-$17.5bn by the end of the year.

In my view, investors may be underestimating the earnings potential of this business. Glencore said this morning that it expects to generate annualised free cash flow of $4.5bn at current commodity prices. Free cash flow was $2.4bn during the first half, so this target certainly appears possible.

Based on Glencore’s current £26bn market cap, free cash flow of $4.5bn would give the firm’s stock a forecast price/free cash flow ratio of 7.6. That’s very cheap indeed. If Glencore can deliver on this promise and hit debt reduction targets, then the shares could have further to climb.

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