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

Don't call it a comeback, but following a multi-week low in the broad-based S&P 500 (SNPINDEX:^GSPC) earlier this week, the iconic index roared higher for a second straight day on the heels of positive economic data to close at another all-time closing high.

Pushing the S&P 500 decisively higher today was positive data from the Mortgage Brokers Association, as well as the release of the December Producer Price Index report.

The weekly MBA report on loan originations showed a robust increase of 11.9%, which follows a gain in loan originations of 2.6% in the prior week. If consumers finally understand that lending rates are still historically low by all measures even though rates have moved higher than their May 2013 lows,  then the housing and mortgage service sector could still have life.

Similarly, the December PPI, a monthly measure that aggregates costs from nearly all goods-producing sectors and some 25,000 establishments, showed an increase of 0.4%, which compares to a contraction of 0.1% in November, and market expectations of a jump of 0.2% to 0.4%, depending on the source. While higher costs for businesses are rarely a good thing, this cost inflation is often a sign that economic times are strong, and could give businesses ample reason to boost organic growth by passing along price hikes to consumers.

By day's end, the S&P 500 had advanced by 9.50 points (0.52%) to close at 1,848.38, the S&P 500's first new record high of the year.

Leading all companies to the upside today is small-cap clinical-stage biopharmaceutical company Chelsea Therapeutics (NASDAQ:CHTP), which rocketed 91.7% higher after announcing a positive recommendation from the Food and Drug Administration's advisory panel with regard to Northera, a drug designed to reduce dizziness in patients with Parkinson's disease. The FDA's panel voted 16-1 in favor of recommending Northera for approval, which is a bit of a surprise given that the FDA had previously rejected Northera because of long-term efficacy concerns. The vote is even more baffling considering that the FDA advisory panel's briefing documents on Friday alluded to a complex decision at hand. While Chelsea shareholders should certainly be thrilled with today's decision, I would reserve my optimism for a later date as the FDA isn't required to listen to the advice of its panel, and Northera's long-term efficacy could still come into question.

Data center solutions provider Datalink (NASDAQ:DTLK) saw its shares soar 37.6% after it updated its fourth-quarter sales and EPS guidance after the bell last night. According to the company, it now anticipates reporting revenue of approximately $174 million for the quarter, up from its own previous guidance of $160 million to $170 million, and the current consensus estimate of $167 million. In addition, it upped its EPS guidance to a fresh range of $0.33-$0.37 from its prior guidance of $0.24-$0.30, and Wall Street's estimate of $0.25. Although no commentary was provided with the release, it's clear evidence that spending on big data centers and cloud-based software is only increasing, potentially positioning Datalink for years of strong growth.

Finally, small-cap biopharmaceutical company Amarin (NASDAQ:AMRN), which is focused on developing therapies to improve cardiovascular health, gained 15.9% in anticipation of a decision by the Division of Metabolism and Endocrinology Products (DMEP) with regard to its special protocol assessment for Vascepa. In October 2013, DMEP rescinded the SPA for the Anchor trial, but DMEP had set Jan. 15 as the date by which it would make its determination on a reinstatement or not. After the bell, however, Amarin released news that its reinstatement request had been indefinitely delayed. Given the likely need to run lengthy safety trials to appease the FDA with regard to expanded Vascepa usage, I would keep my nose clear of Amarin following today's move higher.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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