LONDON (Reuters) - Countries making up over 60% of the world's economic output and more than half of its population hold elections this year.

Markets face a "ballot box bombshell", financial services group Morningstar says, adding: "prior experience of this kind of event risk shows big changes can cause sell-offs".

Here's a look at the elections that matter for markets, in roughly chronological order for the coming year.

1/ TAIWAN

Date: Jan 13

Back story:

Taiwan's ruling Democratic Progressive Party (DPP) is competing mainly with the opposition Kuomintang (KMT) for the presidency and legislature.

A DPP win would be the third consecutive victory for a party China calls separatist, potentially fuelling Beijing's determination to control Taiwan. The KMT traditionally favours closer ties with China but denies being pro-Beijing.

Market risks:

Taiwan is the main flashpoint in U.S.-China tensions. Investors, fearing sharpened trade tariffs, have slashed China allocations.

A full-blown Chinese invasion of Taiwan, while seen as unlikely in 2024, would be a potentially catastrophic risk to global markets, including potentially halting advanced chip-making and wiping $1 trillion off annual global economic output, U.S. officials said.

2/ EUROPE

Dates: March 10 (Portugal), June 9 (Belgium), June 6-9 (European Parliament), autumn/winter (Croatia), November (Romania), to be confirmed (Austria)

Back story:

November's shock win for Geert Wilders's Freedom Party in the Netherlands galvanized the Eurosceptic far-right. Its namesake leads Austria's polls. Portugal's Chega party's vote may double, though left parties lead there.

Crucially, far-right parties eye gains in the European Union's legislature, vowing to toughen migration policy and soften green reforms.

Market risks:

Italian stocks and bonds, Europe's top 2023 performers, may suffer if gains for eurosceptic parties are seen as weakening the commitment to European integration.

The EU raising joint debt to back the post-pandemic recovery has helped reduce the perceived riskiness of Italian debt.

With the EU parliament heavily involved in legislation and electing the next head of the bloc's executive, watch the readout on further support for Ukraine and climate policy.

3/ RUSSIA:

Date: March 17

Back story:

Vladimir Putin, who was handed the presidency by Boris Yeltsin on the last day of 1999, is certain to win another six years in power. Polling shows Putin enjoys approval ratings of above 80% in Russia. Opposition politicians say the election is a carefully stage-managed imitation of democracy.

Key market risk:

In the campaign, Putin may reveal more of his thinking about the war in Ukraine. Putin has warned the West any attempts to meddle in the election will be considered an act of aggression.

    Western governments such as the United States and Japan are considering seizing frozen Russian assets such as cash and government bonds held by its central bank overseas. Russia has said it will retaliate if that happens.

    Russia's economy has been boosted by massive increases in defence spending on the war, though stubborn inflation fanned by a sharp rouble depreciation has forced interest rates higher.

4/ INDIA

Date: April-May, TBC

Back Story:

Narendra Modi is expected to win a third term as prime minister leading the Hindu nationalist Bharatiya Janata Party (BJP) in national elections. Investors moving cash out of China have turned to India.

Key market risk:

Persistent inflation could hurt the BJP. Modi would need to form a coalition if it doesn't win an outright majority.

Key commodity exporter India has roiled markets by restricting rice, wheat and sugar exports. A shift back to fiscal populism risks pushing up India's fiscal deficit which would need funding from potentially record high domestic market borrowing.

5/ MEXICO

Date: June 2

Back story:

Presidential election will involve a full Congress reshuffle and nine state elections. Polls give incumbent National Regeneration Movement (Morena) party and its candidate, ex-Mexico City mayor Claudia Sheinbaum, a wide double-digit lead.

A more balanced Congress preventing constitutional changes from populist Morena is anticipated. But given the success of current President Andres Manuel Lopez Obrador's spending drives, Sheinbaum is expected to follow suit.

Key market risk:

Heftier spending could pull down Mexico's peso and hurt government bonds.

6/ SOUTH AFRICA

Date: May-August 2024 (TBC)

Back story:

The ruling African National Congress risks losing its parliamentary majority in elections for the first time since Nelson Mandela led it to power in 1994.

Economic turmoil, power cuts, austerity and graft allegations have alienated voters. The ANC may need to partner with the Democratic Alliance or the Marxist Economic Freedom.

Key market risk:

Pre-election, the government could ease austerity, pushing up debt. If the ANC allies with a leftist party, social spending could rise. Worries about a weak currency and public finances could slow down rate cuts.

7/ UNITED STATES

Date: Nov 5

Back story:

Donald Trump is predicted to win the Republican nomination in primaries in the coming months, setting the stage for a tight battle with Democrat incumbent Joe Biden - a rerun of the 2020 election that ended with a pro-Trump mob storming Congress in an attempt to block certification of Biden's victory.

Trump now faces criminal trials in four jurisdictions and an array of other legal cases, while he still claims falsely that the 2020 election was stolen. Biden calls his opponent a threat to democracy who would seek vengeance on his many foes if he regains power.

Market risks:

Markets shrugged off the violence that followed the election four years ago. But given the heated rhetoric on both sides this time around, a Trump-Biden rematch could still worry investors over the risk of social unrest.

A bitter election could affect consumer sentiment as the world's biggest economy seeks to avert a recession from the lagged effects of aggressive interest rate rises.

The dollar could swing on election probabilities.

Stocks could be hurt by caution over U.S.-China tensions if the parties harness the popularity of trade barriers, with analysts saying higher tariffs would fuel inflation, force up the dollar and hurt the yuan, euro and Mexican peso.

Spending cut pledges by either party could upend a complex but popular U.S. bonds trade that wagers government borrowing will increase. And watch oil: Trump favours more U.S. drilling, which Biden has reined in.

8/ BRITAIN

Date: due by Jan 2025, expected by end-2024

Back Story:

The opposition Labour party under centre-left candidate Keir Starmer leads the ruling Conservatives in the polls.

Market risks:

Pre-election, a stagnant economy and tight fiscal budget mean government bonds could be unsettled by any surprise spending promises. A March 6 budget might well contain new tax cuts.

Labour plans to loosen planning rules, in a risk for house-builders and make targeted changes to tax rules which could hurt energy companies. It also wants closer relations with the European Union following Brexit, which could boost sterling.

9/ VENEZUELA

Date: 2024 TBC

Back Story:

Incumbent Nicolás Maduro has an advantage in presidential elections, with main opposition candidate, María Corina Machado, banned from participating due to alleged crimes such as supporting U.S. sanctions on Maduro's government and backing former opposition leader Juan Guaido.

Key Market Risk:

In October, the U.S. lifted oil sanctions for six months and debt sanctions indefinitely, allowing U.S. investors to trade in some bonds in exchange for talks to ensure fair and free elections.