Help ! Oligopolistic market question

Hi guys, i got very confused by the answer of this question from official curriculum:

Q: Over time, the market share of the dominant company in an oligopolistic market will most likely :
A. increase
B. decrease
C. remain the same
Answer: B

My thoughts : in an oligopolistic market, the dominant company’s market share will INCREASE as price war between other companies ruling out some small players. But the answer from curriculum says market share of the dominant company will DECREASE as profits attract new entries. To me, it is only a short-term thing that market share of the dominant decrease, on long-run, the market will reorganise as the dominant reduce price and rule out the small players so as to take back its market share. So the correct answer for me is A or C (if two effects offset each other).

Can someone tell me what as I missing pls ?

Thanks in advance,

Hi -

The most-dominant firm also has biggest target on its back because it is earning the most profits. Bank robbers rob banks because that’s where the money is, and new companies go after fat & happy incumbents in an oligopoly or monopoly market because that is where the market share and profit are.

Unless there are significant barriers to entry, then most likely over time that competitive advantage will erode as new entrants come in and compete for and get some of those outsized returns and market share. Over time that oligopoly will deflate into something closer to Perfect Competition where there are no outsized returns. Total number of firms in a perfectly competitive market are > than # of firms in an Oligopoly, and likewise, market share of individual firms in a competitive market is < market share of Oligopoly companies.

Your scenario might hold true in a market where there are significant barriers to entry, such as in a highly regulated industry. (eg, a public utility or space travel). But absent significant barriers to entry, then over time the market will get more and more competitive and whatever edge that powerful incumbent had, will erode and with it, market share and profits.

i think its vise-versa as in long term everything is variable a new firm definately enter the market