Small-cap stocks underperformed the major indices for the second straight session, as several small health care names took their lumps.

Drugmaker Acusphere ( ACUS), of Watertown, Mass., lost 11% to $2.26, after agreeing to sell $20 million in stock and warrants to institutional investors under an existing shelf registration. Net proceeds are expected at around $18.7 million.

Geron ( GERN) also took a hit after failing to announce big news on its GRN163L cancer treatment. The California-based company only reported that phase I/II testing has yielded positive results in pharmacokinetics and tolerability. Shares tumbled 8.5% to $7.97.

Cyberonics ( CYBX), which makes devices for epilepsy treatment, slid 7.8% to $16.59 on disappointing financials. The Houston-based company's loss more than doubled to 42 cents a share -- 7 cents worse than the mean Street target from Thomson Financial. Revenue came in just shy of consensus.

Geron and Cyberonics pressured the Russell 2000, which was recently off 0.9%, or 7.83 points, to 825.35.

But a few other Russell 2000 components -- namely, Pier 1 Imports ( PIR), Robbins & Myers ( RBN) and Take-Two Interactive Software ( TTWO) -- jumped on analyst upgrades.

Goldman Sachs raised home-furnishings retailer Pier 1 to buy from hold, saying a turnaround might be around the corner. Ohio's Robbins, which makes equipment and systems for a variety of industries, was likewise upped to buy at KeyBanc Capital Market. And Take-Two was upgraded by both JPMorgan and Kaufman Brothers on the heels of last night's earnings report.

Pier 1, Robbins and New York-based Take-Two were all recently trading up 4.7% or more, the latter two in support of the S&P SmallCap 600. Still, the index was down 0.8% at 428.35.

Elsewhere in positive territory, VirtualScopics ( VSCP), of Rochester, N.Y., soared 24% to $1.40, after inking a five-year clinical-trials-services deal with a "leading" biotech company. Financial terms weren't disclosed.

Filtration-products maker MFRI ( MFRI) quintupled its first-quarter per-share earnings compared with the year-ago period. The company reported earnings of 15 cents a share, beating two analysts' estimates by a nickel. And Georgia's Exide Technologies ( XIDE) sharply narrowed its fiscal fourth-quarter loss to 35 cents a share. A year ago, the lead-acid-batteries maker lost $2.98 a share.

Shares of Illinois-based MFRI were leaping $3.12, or 13%, to $26.52. Exide advanced 8.1% to $8.25.