Dear Mr. Berko: Back in the summer of 2009, you told me to buy a company called Universal Display for my individual retirement account. The company has thousands of patents for the development of organic light-emitting diode technology, which is used in various solid-state lighting applications. It sounded good, so I bought 300 shares at $6.50 and sold it at $14 a year later. Then, in an email, I asked for another recommendation. You told me to buy Universal Display back and you would tell me when to sell it. Eight years has gone by, and the stock is now $185 a share and is 57 percent of my IRA value. I haven’t heard a word from you, but I’m wondering whether I should keep the stock or sell it.

— TR, Fort Walton Beach, Fla.

Dear TR: You’re very welcome!

Since then, Universal Display Corp. (OLED-$185) — a company with zero debt, 200 employees and 47 million shares outstanding — watched its capitalization rocket from $175 million to $8.7 billion. As you alluded to, Universal is a pioneer in the high-growth field of OLED technology. It owns 3,782 patents and has long-term contracts with some of the biggest users in the industry. Now the electronics industry is prepared to use OLED technology in smartphones, computers and numerous other products. This is a disruptive technology, meaning a product that takes root as a simple application in a new market and relentlessly moves up, eventually displacing competitors in an established market. Few civilians know about Universal Display, and those who do are totally bonkers over a potential partnership with Apple, which may use OLED’s materials in 200 million-plus iPhones.

There’s also an extraordinary stock I recommended in February, Accelerate Diagnostics (AXDX-$25). AXDX is another disruptive technology company. (Imagine the steam engine versus sailing ships, telephones versus telegrams, electric lights versus oil lamps.) It will remarkably change the way medicine is practiced throughout the world. AXDX uses a thimble of blood, a bit of fluid from your lungs, a body tissue sample or your saliva and performs its medical magic. AXDX has a proprietary, almost science fiction, in vitro diagnostic platform using genotypic technology (your personal gene schematic) to identify infectious pathogens. The AXDX system can recommend a regimen of prescriptions that should interact favorably with your specific genetic makeup. There’s no guessing, no costly or painful trial and error, no muss, fuss or bother. The analysis is completed in minutes, not days; the time of treatment is minimized; hospital stays are reduced; and the cure costs are hugely lower.

I recommend you sell 100 shares of OLED tomorrow and use the proceeds to buy 700 shares of AXDX. Then be mindful not to sell those shares when they reach $40 — or $70 or $125.

Standard & Poor’s, Market Edge, Zacks, Credit Suisse, Morgan Stanley and Argus Research don’t give a hoot for AXDX. However, the sentiment among professionals I respect is very positive. And after talking with various doctors, I know I’m very confidently bullish.

Address financial questions to Malcolm Berko, P.O. Box 8303, Largo, FL 33775, or email him at