The Month's Biggest Stock Losers: How to Tell a Sell-Off from an Ex-Dividend Drop

The ranking below sorts Moscow Exchange stocks by one single criterion — the change in price over a calendar month, from worst to best. It is not a list of stocks that "got cheaper", and still less a list of "undervalued" names: a price may have fallen because the company lost its market, or because a dividend was detached from the share or the par value of the security changed. The ranking calculates the difference between quotes and knows nothing about the reason behind it. You will have to look for the reason yourself, and the sections below show exactly where.

What exactly is measured

The closing price at the start of the period and the latest known price are taken, the relative change is calculated, and the stocks are arranged in ascending order — which means the deepest losses end up at the top. The sample is limited to shares traded on the Moscow Exchange; the list is recalculated daily, so the contents of the table today and a day later may not match.

It matters that the comparison runs between securities, not within a single security. Sitting next to each other in the list does not imply kinship: a large issuer after a weak report may appear beside an illiquid stock that was moved by a couple of trades. The second case is not a market valuation but an artefact of a thin order book. Turnover helps to tell them apart: if there is almost no trading, the price move carries no information about the value of the business. This is covered separately in the piece on the most actively traded stocks.

Why a month is an especially noisy horizon

An annual ranking averages out randomness: over a year a stock passes through several reporting periods, and a lasting deterioration of the business shows through. A month works differently — over such a stretch, events dominate, not trends. An earnings release, a dividend decision, a change in index composition, a large sale by a majority shareholder, tax news for the sector — any of them overrides the fundamental dynamics and carries the stock to the top of the losers' list.

A practical consequence follows: the monthly ranking is good as a detector of events and poor as a detector of problems. It answers the question "what has something happened to", not the question "what has got worse". If it is the second question you need answered, look at the annual ranking of the worst performers — the method is the same, but on a horizon where the noise is partly dampened.

The fall that never happened

Some of the positions in such a list are falls in form only.

The ex-dividend date. On the day the stock starts trading without the right to the nearest payout, its price drops mechanically by roughly the amount of the dividend. The holder has lost nothing: the value has simply moved from the quote into the forthcoming payment. But a ranking of price changes does not know this and faithfully shows a loss. It has to be checked against the payout calendar — whether the ex-dividend date fell within the calculation period:

A change in par value. In a stock split the price of one share falls proportionally, while the investor's stake in the capital does not change. This is pure accounting arithmetic; see the par value of a share and the piece on why the price of one share says nothing about the company.

A shift between share classes. At an issuer with two types of shares, the ordinary and the preferred lead lives of their own and diverge in performance for reasons unrelated to the business — the details are in the breakdown of ordinary and preferred shares.

What the ranking does not let you conclude

You cannot conclude that the stock will bounce. A return to the previous price is a hypothesis, not a property of the fall; a stock that fell on a deteriorating business keeps falling just as readily as it recovers.

You cannot conclude that the market got it wrong. A fall more often means that participants have revalued future cash flows than that they failed to understand the situation.

You cannot conclude that the company is in trouble. An ex-dividend date, a split, removal from an index, a large one-off sale — not one of these events says anything about the state of the business.

And you cannot compare the positions with each other as "worse/better": a difference in percentages does not mean a difference in the quality of the issuers.

How to read the table step by step

Step 1 — strip out the mechanics: check the period against the ex-dividend dates and corporate actions. Step 2 — check liquidity: when turnover is low, the price move is not informative. Step 3 — find the event: open the financial reports and the events calendar for the same period. Step 4 — only after that move on to assessing the business. The sequence of actions for this step is gathered in the checklist before buying a stock.

The full list of securities with current quotes is in the stocks section; unfamiliar concepts from the table are explained in the glossary.