Many companies are buying back their shares now. It's not slick, it's just conventional wisdom since there isn't the business confidence to expand with the uncertainties facing the economy. Everybody's doing it and no big deal either way. Companies have cash and they don't know what to do with it.
The stock exchange is merely an auction market, just like a farm auction, and the little guy with 100 shares and equal opportunity with the gazillion share buyer. It's based on who is willing to pay what price. If somebody shows up to buy 100 shares for a few pennies more than a pending huge order, the little guy wins and gets the stock. The whole thing is the marvel of capitalism.
For many years, Monsanto was a $10 to $20 dog that was a weight on anyone that owned it and wished they never heard of it. Come Roundup and Roundup Ready stuff, however, and those with the foresight to recognize what an amazing development it was and what the future held did very well. We may not like Roundup for ideological or emotional reasons but the market (which is a collection of all voices with money at stake in the stock) gave it two thumbs up.
More likely affecting Monsanto shares was that a lot of people sold the stock "short" anticipating a price drop. When it didn't happen, they now have to chase it higher in price to get out of that position and the price can rise from that demand.
Move along people; nothing to see here.