BioVeris has been felled by a family feud.

Celera Genomics isn't going to start testing its new drug this year after all.

MedImmune's spray flu vaccine was a flop.

Human Genome Sciences still hasn't delivered on the potential that made it a $100 stock -- four years ago.

Summer is always bad for biotechnology stocks. This summer is particularly nasty.

"For a sector that typically runs hot and cold, biotechs, right now, are downright frosty," writes Adam Feuerstein of TheStreet.com, an online biotech commentator.

Many of the local biotechs are suffering from self-inflicted ailments, but even the others are struggling in the stock market.

Martek Biosciences regularly tops lists of top-rated stocks -- it's one of only 11 stocks in the Russell 2000 index to get straight "buy" ratings -- but investors aren't buying. In the past three months, Martek stock has fallen from $70 a share to $46.

Only United Therapeutics, which is expected to announce solid second-quarter results tomorrow, has held up against the summer selloff. Even with the success of its pulmonary hypertension drug, United Therapeutics' stock is down about a dollar since January.

To biotech analysts, the summer slump means this is a good time to buy. Biotech stocks are always cyclical, they say, so the time to invest is during the down cycle.

What the pros call "cyclical" however can be a gut-grabbing roller-coaster ride for investors used to the boulevard calm of buying blue chips.

Biotechs are unstable even by the standards of technology stocks. The American Stock Exchange's biotech index, which includes more than just Amex stocks, has fallen 18 percent from its peak earlier in the year. The Nasdaq composite index is off only 13 percent. The Nasdaq peaked in January, so those losses were spread over six months. The biotech index hit its high in April, squeezing its plunge into just three months.

Biotech companies are infamous for falling in and out of fashion. And their seasonal cycle is familiar to analysts. "Biotechnology stocks historically have performed particularly well in the third and fourth quarters as data flow and milestones from major medical meetings typically cause shares to perform positively," say analysts Edward H. Nash and Robert S. Gilliam IV of Legg Mason in Baltimore.

"They are so catalyst-driven and news-flow-driven that when the news flow slows down, people don't feel comfortable parking the money there," says Jim Reddoch, the top biotech analyst at Friedman Billings Ramsey in Arlington. "Summer is one of those times."

Reddoch says the summer slump for biotechs typically starts after the meeting every June of the American Society of Clinical Oncology. Biotech companies are heavily focused on developing new cancer drugs. The ASCO conference is where the latest cancer drug research results are revealed. This summer, the biotech index took a pop after ASCO, then continued its decline.

Other catalysts for the industry coming up in the next few months include the Interscience Conference on Antimicrobial Agents and Chemotherapy, the Infectious Disease Society of America meeting and the annual meeting in December of the American Society of Hematology.

Research results announced at scientific conferences can benefit specific stocks, but like many other industries, biotech stocks often move as a pack. They also tend to suffer as a group when the whole market is squishy.

With the biotech cycles in mind, Reddoch said his strategy is to "be selective during this time and invest in companies that have catalysts between now and the end of the year and have values that are defensible."

The Legg Mason biotech team issued a broad recommendation of biotech stocks last week. "The biotechnology sector will significantly outperform the other major indices over the next 12-18 months," it predicted.

Both Legg Mason and Friedman Billings Ramsey do investment banking for biotech firms, and their trading desks make markets in many of the local biotech stocks. That means they are well-wired into the industry, but also that they have a vested interest in its success.

Because biotech stocks are so volatile, there are traders who advocate a contrarian approach to the whole industry. The best way to make money in biotech, they contend, is to bet the stocks will go down, "selling them short." Short sellers borrow shares, then sell them. If the stock declines, they can buy back the shares they sold at a lower price, repay the borrowed stock and pocket a profit. Short sellers have made a lot of money in biotech this year.

But in a note to clients last week, the Legg Mason analysts argued that biotech stocks have fallen below the valuations at which they usually trade and are due for a rebound.

Citing 10 "biotech bellwethers," including MedImmune, they calculated that over the past 10 years, those stocks have sold for a little more than 39 times their projected profits for the year ahead. As of last Tuesday, the group was trading for about 35 times projected profits.

MedImmune's stock (Nasdaq: MEDI) has been one of the year's biggest disappointments to biotech investors. Trading for the last month in the $23 range, it was $39 last summer, when investors were enthused about FluMist, a nasal spray flu vaccine that went on the market last fall. FluMist was a rare biotech bust, with sales a fraction of what had been projected. Priced at about $85 a dose, FluMist could not compete with $15 flu shots. Legg Mason projects it will be three years or more before FluMist becomes a significant profit generator, but MedImmune is making money on Synagis, a treatment for viral respiratory infections.

Celera Genomics dropped $2 a share in a matter of days last spring after the company delayed testing of a promising new drug. Down from about $16 a share in January to just under $11 last month, the stock has climbed about a dollar a share in the past week. The catalysts included a reduction in the quarterly loss to $5.8 million from $19.4 million, progress on development of a new osteoporosis drug for Merck and new research ventures with several big drug companies. Celera is a division of Applera Corp. but has its own tracking stock (NYSE: CRA).

Human Genome Sciences on Friday reported its quarterly loss grew to $58.5 million from $47.4 million in the same period a year ago. The stock (Nasdaq: HGSI) is down from $14 in April to about $10 and ticked up slightly after Friday's announcement. With $1.1 billion in the bank to finance research based on genetic analysis, HGSI has more than a dozen drugs in the pipeline.

Martek Biosciences reported second-quarter sales of its infant formula supplements increased to $41.9 million from $26.4 million but, because of big investments to increase production, profit grew only slightly, to $3.4 million from $3.1 million. Trading for $70 earlier in the year, the stock (Nasdaq: MATK) bottomed out at $45.69 last Monday and rebounded to close at $47.32 on Friday.

BioVeris shares are down from $17 to $7-and-change as the result of allegations of improper use of corporate funds by Jacob N. Wohlstadter, the son of founder Samuel J. Wohlstadter. BioVeris stock trades on Nasdaq under the unusual symbol BIOVE. The E signifies that the company has not filed audited financial reports, which are held up by the dispute over expenditures.

For the stock of United Therapeutics (Nasdaq: UTHR), the key catalyst isn't likely to be tomorrow's earnings report but government approval, expected this fall, of a new version of Remodulin, the company's treatment for hypertension. The new version could quadruple Remodulin sales, which is why, analysts say, the stock had held its own.