I have a stock certificate that is in 3 names. My mom, who is deceased, my brother and myself. The stock, (Holobeam), now HOOB, is no longer on the Dow but was $19 a share and now is $38. What happens when a stock is no longer on the market. Wonder if it a good idea to sell. Thanks.
The DOW is just an index, which is simply a group of stocks meeting the criteria for inclusion. In the case of the DOW, it's the 30 US stocks with the largest market capitalization, but other indices include many lesser stocks (such as the S&P500 or the Russell 2000). The fact that Holobeam is no longer a constituent of the DOW30 probably shouldn't be taken in and of itself as a signal to sell the stock.
As far as I can tell, HOOB stock is still trading on the Nasdaq exchange. However, it is extremely ill-liquid, which means that there are very few people willing to buy or sell it. Whether or not this would work to your advantage is almost entirely down to luck - it depends whether there is a keen buyer out there at the time you try to sell.
I'd call it pretty worrisome. HOOB is trading over the counter, in fact, on the pink sheets, so it has been delisted from the major exchanges. It appears that it lacks recent financial disclosures. You'll have to investigate to see if you think it's worth keeping, but trading is thin.
The common way to frame the "should I sell" question is ask yourself "would you buy it today at the current price". If you wouldn't, sell it.
Is sounds like this may be a paper certificate. You will have to research how to present the certificate to a broker to trade it, or if the company has a direct shareholder program. I have periodically been offered to sell "odd lots" to shareholder programs which, if one exists, may be less hassle than other options. As a part of this, your mother's estate administrator should decide if the estate is selling it's interest, or giving it's interest to heirs before the sale.