What happened?

Tuesday is shaping up to be a good day for shareholders of STAAR Surgical (NASDAQ:STAA), which manufactures implantable lenses, and Prestige Consumer Healthcare (NYSE:PBH), which markets over-the-counter (OTC) healthcare products. As of 1:30 p.m. EST today, STAAR Surgical stock was up by 14.7%, while Prestige Consumer's stock was up by 7.7%. The catalyst was recently announced changes to two market indexes involving both companies.

So what

Starting on Jan. 29, STAAR Surgical will replace Prestige Consumer in the S&P MidCap 400, an index that tracks 400 mid-cap companies in the U.S. equity market. It is one of the most widely followed mid-cap indexes, and eligibility requirements include a certain level of liquidity and financial viability. Meanwhile, on the same day, Prestige Consumer will take the place of Foundation Building Materials (NYSE:FBM) in the S&P SmallCap 600.

Hand drawing upward-bound graph.

Image source: Getty Images.

While changes to more-famous indexes such as the S&P 500 tend to attract more attention, new additions to smaller ones like the S&P SmallCap 600 and the S&P MidCap 400 can also generate some excitement among investors, and that seems to be what's happening today with STAAR Surgical and Prestige Consumer. 

Now what

For long-term investors, these changes mean little in the grand scheme of things, and so does the boost that STAAR Surgical and Prestige Consumer are experiencing as a result. The important thing to focus on is the prospects of both these healthcare companies

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