It can't be said that the week closed on a high note -- certainly not for the broader market anyway.  There were some individual standouts like Amazon.com (AMZN 530.50, +48.32), Visa (V 74.80, +3.05), Starbucks (SBUX 57.32, +0.76), and Juniper Networks (JNPR 27.54, +1.05), which impressed investors with their earnings results, yet there were far more losers on Friday than winners as economic slowdown concerns and valuation concerns got the better of market participants.

The slowdown concerns were rooted in a variety of factors:

The Flash PMI reading for China dropping to a 15-month low of 48.2 in July and signaling a contraction in manufacturing activity

Weaker than expected PMI readings out of Germany and France that pointed to a deceleration in growth momentum

The continued drop in crude futures ($48.13, -0.26), which traded further into bear market territory having fallen more than 20% from their June peak; and

The disappointing report on new home sales in the U.S., which declined 6.8% in June to 482,000 units (Briefing.com consensus 550,000)

The valuation concerns, meanwhile, revolved in large part around two factors:

Biogen Idec (BIIB 299.85, -85.20) cutting its FY15 revenue and EPS guidance, which unleashed a wave of selling interest in that stock and peer companies in the highflying biotech group; and

The weak economic data, which raised questions about future earnings prospects

The early strength in Amazon.com helped the market stand its ground for a bit, yet selling interest picked up steadily after the New Home Sales report at 10:00 a.m. ET.  For most of the day thereafter, the major indices logged a progression of new lows before the steady selling activity subsided entering the final hour of trading.

There was some chatter that a proposal by Democratic presidential candidate Hillary Clinton to raise the short-term capital gains tax on top-bracket payers was responsible for today's negative price action.

While such a headline might have contributed to the negative sentiment that was already in place in the wake of Biogen's warning and the disappointing economic data, it would be overstating things to list that proposal as the cause of today's weakness.  That's because Mrs. Clinton hasn't even been elected president, let alone won her party's nomination.  Moreover, passage of such a proposal is no sure thing if there is a Republican-controlled Congress on the other side of the 2016 presidential election.

The worst-performing areas of the day were a manifestation of the two bigger issues noted above.  To that end, the health care sector (-2.5%) topped the list of losers as the weight of losses in the biotech space, evidenced by a 4.0% drop in the iShares Nasdaq Biotechnology ETF (IBB 378.01, -15.74), weighed heavily.

In turn, the economic worries showed up in the underperformance of the materials (-2.2%), energy (-2.0%), and industrials (-1.3%) sectors, as well as the front end of the Treasury yield curve, which is most sensitive to rate hike expectations.

Longer-dated maturities were little changed, but the 2-yr note saw its yield drop two basis points to 0.68%.

Elsewhere, gold futures settled down 0.8% at $1085.60/troy ounce, but ran back to $1100/troy ounce in extended action on short-covering interest before losing momentum.

NYSE volume was on the light side today at just 645 million shares.  The lopsided nature of today's trade was seen in the A/D line, which favored decliners by a better than 2-to-1 margin at the NYSE and a 3-to-1 margin at the Nasdaq.

The earnings results will continue pour in next week, but economic data and the Federal Reserve will also be in the limelight with the Federal Open Market Committee policy decision on Wednesday and the advance estimate for Q2 GDP on Thursday.