Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

This morning's ADP report showed the private sector adding 130,000 jobs this month, short of the 150,000 that economists had forecast. Furthermore, the September figure was revised down from 166,000, to 145,000. Those numbers are simply more reason that it's scarcely conceivable that the Fed would announce a taper in its bond-buying program this afternoon. Markets are holding their breath for now, with the S&P 500 and the narrower, price-weighted Dow Jones Industrial Average (^DJI -0.11%) having moved less than 0.1% at 10:10 a.m. EDT.

Professional social-networking site LinkedIn (LNKD.DL) reported its third-quarter results after yesterday's market close. The quarter was rock-solid, so why isn't the market rewarding the stock this morning? Shares are down 8% so far.

First, the numbers: The company beat Wall Street expectations for the top and bottom lines, with revenue of $393 million versus a forecast of $385 million and earnings per share of $0.39 (ex-items) against $0.32. That represents 56% year-on-year growth in revenue and a stunning 77% increase in EPS.

All three of LinkedIn's businesses -- talent solutions, marketing solutions, and premium subscriptions -- performed well, contributing pretty evenly to growth, and the number of members rose 38% to 259 million.

However -- and you knew it was coming -- those numbers now belong in the company's operating past, and the market is focused on the future, which is where LinkedIn disappointed (in relative terms), offering guidance for fourth-quarter revenue of $415 million to $420 million, whereas analysts had been looking for $438 million.

That might not look like a big miss; after all, the midpoint of the guidance range is less than 5% short of analysts' estimate. The trouble is that with a stock valued at 128 times the forward EPS estimate for the next 12 months, the market can't let the smallest miss slip by.

LinkedIn is a terrific business (much higher-quality than Facebook, for example); the numbers it's putting up prove that, and I expect its franchise to go from strength to strength. However, the stock's valuation is a different matter altogether: Like that of many stocks in the social-networking sector, it looks stretched, and that means shareholders can expect a bumpy ride as growth expectations meet tangible results.